Justice HANKINSON
delivered the opinion of the Court,
in which Chief Justice PHILLIPS, Justice ENOCH, Justice BAKER, Justice ABBOTT, Justice O’NEILL and Justice GONZALES joined.
This original mandamus proceeding arises out of a class-action lawsuit. Rela-tors, defendants in the underlying proceeding, present two issues for determination. First, have Plaintiffs sent proper notice of their claims under the Deceptive Trade Practices Act (DTPA)? Second, are Rela-tors entitled to an order bifurcating class and merits discovery? We conclude that Plaintiffs’ DTPA notices, which demanded settlement on behalf of the entire putative class, were proper. We also conclude that, because Relators did not clearly distin[176]*176guish class and merits discovery, Relators are not entitled to an order bifurcating the two. Accordingly, we deny the "writ of mandamus.
Envo-Tech, Inc., Jett Jones, Sheryl M. Nickerson, and Leon M. Andrews, III, filed a class-action lawsuit against 636 Texas motor vehicle dealerships, alleging that the dealerships committed fraud, conspiracy, and DTPA violations by passing on their inventory taxes to consumers as an itemized charge in addition to the advertised or negotiated purchase price. Plaintiffs allege that “each Defendant conspired and agreed to charge the so-called ‘tax’ to each purchaser, to mislead and fail to inform each purchaser as to the nature and legal obligation to pay such tax, and to require ‘add-on’ of the so-called tax as a condition to purchasing the vehicle in Texas.” Plaintiffs seek to represent consumers who bought vehicles from the dealers since January 1,1994.
Relators, 598 of the 636 defendant dealers, moved to abate on the ground that Plaintiffs did not send then-adequate DTPA notices. They also moved for a protective order to abate all merits discovery until after class certification, urging that the broad, expensive classwide discovery the Plaintiffs sought would be unnecessary if the class were not certified. Relators further objected to Plaintiffs’ interrogatories and requests for production. The trial court denied the motion to abate and the motion to bifurcate. It sustained in part and overruled in part Relators’ objections. Relators petition for mandamus relief from the two orders denying abatement and bifurcation. They do not challenge the trial court’s ruling on the specific discovery objections. We address the abatement and bifurcation issues in turn.
I
Standards for Mandamus
Mandamus will lie only to correct a trial court’s clear abuse of discretion when no adequate remedy by appeal exists. See Walker v. Packer, 827 S.W.2d 833, 839-40 (Tex.1992). A trial court abuses its discretion if it erroneously denies a DTPA defendant’s timely request for abatement. See Hines v. Hash, 843 S.W.2d 464, 469 (Tex.1992); Tex. Bus. & Comm.Code § 17.505(d). Also, “[a]n order compelling discovery that is well outside the proper bounds is reviewable by mandamus.” In re American Optical Corp., 988 S.W.2d 711, 713 (Tex.1998). Therefore, we consider whether the trial court abused its discretion by denying Relators’ pleas in abatement and motion for protective order.
II
DTPA Notice
Before filing a DTPA claim, a consumer must timely advise the defendant “in reasonable detail of the consumer’s specific complaint and the amount of economic damages, damages for mental anguish, and expenses, including attorneys’ fees, if any, reasonably incurred by the consumer in asserting the claim against the defendant.” See Tex. Bus. & Comm.Codb § 17.505(a). Upon receipt of the notice, a defendant may establish a defense to the suit as a matter of law by tendering the full amount of damages claimed plus a reasonable amount for fees and expenses. See id. § 17.506(d). Alternatively, a defendant may establish a defense to the amount of damages by offering to tender an amount of damages that is substantially the same as, or more than, the damages the factfin-der ultimately awards. See id. § 17.5052(g). If a consumer files a DTPA suit without sending notice, the defendant is entitled to abatement of the suit until sixty days after proper notice is sent. See id. § 17.505(d), (e).
Plaintiffs did not send the required DTPA notices before filing suit. After Relators filed pleas in abatement complaining of that omission, Plaintiffs sent Relators belated notices demanding that Relators reimburse all consumers who [177]*177paid an itemized vehicle inventory or similar tax since January 1, 1994, plus expenses incurred both before and after suit was filed. Relators contend that the notices are not proper under section 17.505(a) because they demand relief for the class, not just the named Plaintiffs, plus expenses incurred after Plaintiffs filed suit. They argue that before a DTPA action can proceed, the consumer must demand a settlement limited to the named consumer’s own economic and mental anguish damages and presuit expenses, and that the demand cannot include damages sought on a class’s behalf.
As originally enacted in 1973, the DTPA specifically authorized a plaintiff to give notice on behalf of an uncertified class. See Act of May 4,1973, 63rd Leg., R.S., ch. 143, 1973 Tex. Gen. Laws 322, 330. In 1977, the Legislature repealed the consumer class provisions. See Act of May 6, 1977, 65 th Leg., R.S., ch. 216, §§ 10-13, 1977 Tex. Gen. Laws 605. Relators argue that these deletions signified a legislative intent to either eliminate DTPA class actions altogether or empower defendants to unilaterally preempt DTPA class action suits by tendering full payment to only the named plaintiffs.
We disagree. Several commentators have pointed out that the likely motive for repealing the DTPA class-action provisions was the Supreme Court’s revision of Texas Rule of Civil Procedure 42, approved on May 9, 1977, which rendered the DTPA provisions unnecessary. See Jack Pope & Steve McConnico, Texas Civil Procedure Rule Making, 30 BayloR L.Rev. 5, 15 (1978) (“To avoid interfering in this area the Texas Legislature then repealed the sections of the Texas Business & Commerce Code which had authorized class actions in the limited area of deceptive trade practices.”); William V. Dorsaneo, III, Creditor’s Rights, 32 Sw. L.J. 245, 268 n. 198 (1978) (“The general provisions of the rule rendered the special class action provisions of the DTPA unnecessary.”); see also America Online, Inc. v. Williams, 958 S.W.2d 268, 274-75 (Tex.App.— Houston [14 th Dist.] 1997, no writ); Mahoney v. Cupp, 638 S.W.2d 257, 261 (Tex.App.— Waco 1982, no writ) (both adopting same view). The 1973 DTPA class action provisions were patterned after the federal class-action rule, which commentators generally favored over the then-current version of Texas rule 42. See Act of May 4, 1973, 63 rd Leg., R.S., ch. 143, 1973 Tex. Gen. Laws 322, 328 (directing Texas courts to follow federal decisions interpreting Federal Rule of Civil Procedure 23); see also 24 B. Thomas MoElROy, Texas PractiCE: Civil Pre-Trial Procedure §§ 615-17 (1980) (discussing problems with former rule 42). Because the 1977 revisions to rule 42 made it almost identical to its federal counterpart, there was no longer a need to retain the DTPA’s separate class-action provisions.
Relators point out, however, that when the Legislature adopted the class-action provisions of the DTPA in 1973, it also amended article 21.21 of the Texas Insurance Code to add virtually identical class-action procedures. See Tex. Ins.Code art. 21.21, §§ 17-19. The Legislature did not, however, repeal the Insurance Code class-action provisions. Also, the DTPA originally had two provisions relating to class actions — one for procedure, and one for preliminary notice — but only the former would have duplicated amended rule 42. See Act of May 4,1973, 63rd Leg., R.S., ch. 143, 1973 Tex. Gen. Laws 322, 328-30. Relators argue that had the Legislature merely intended to remove any inconsistency between rule 42 and the DTPA class-action procedures, it would have also repealed the Insurance Code class-action provisions and would not have abolished the DTPA’s class-action preliminary notice provision.
Neither the Legislature’s jettisoning of the class-action provisions of the DTPA but not of the Insurance Code, nor its substitution of the DTPA’s class-specific preliminary notice provision with more general notice provisions, reveals an obvi[178]*178ous legislative intent to abolish DTPA class actions. Cf. Butcher v. Owens, 647 S.W.2d 948, 950 (Tex.1983) (warning against use of conjecture to supply legislative intent); Massachusetts v. United N. & S. Dev. Co., 140 Tex. 417, 168 S.W.2d 226, 229 (1942) (“Interpretation by implication is permitted only to supply obvious intent not expressly stated, and never to contradict nor add to a statute.”). Nothing in the legislative history of the 1977 amendments indicates that the Legislature intended to abolish DTPA class actions, and we decline to infer such an intent. If the Legislature had intended to abolish DTPA class actions, it could have expressly done so. We hold that the DTPA permits a consumer to provide preliminary notice on behalf of a putative class.
Courts have long recognized the authority of individual plaintiffs to negotiate settlements on behalf of putative classes. See, e.g., Amchem Prods., Inc. v. Windsor, 521 U.S. 591, 597-98, 117 S.Ct. 2231, 138 L.Ed.2d 689 (1997); General Motors Corp. v. Bloyed, 916 S.W.2d 949, 951 (Tex.1996). Of course, such settlements are ultimately subject to class certification and court approval. See Tex.R. Civ. P. 42(e). Plaintiffs’ demand that Rela-tors reimburse the members of the putative class did not circumvent the DTPA’s statutory notice requirements.
Relators also object to the notices on the ground that Plaintiffs are permitted to demand only presuit damages and expenses, including attorneys’ fees, that Plaintiffs incurred in asserting the DTPA claim. Plaintiffs have demanded more than just presuit expenses. Their April 29, 1998, notice demands $110,000 in “attorneys’ fees to date” and $49,762 in “costs to date.” This complaint, however, challenges the requested fees’ reasonableness, not the notice’s validity. Even if this request was excessive or unreasonable, an issue we do not decide, it did not interfere with Relators’ ability to create a defense to the suit by tendering the amount of economic and mental anguish damages claimed, and the expenses, including attorneys’ fees, reasonably incurred by the consumers in asserting the claims. See Tex. Bus. & Comm.Code § 17.506(d). A defendant’s ability to assert a complete defense depends on the reasonableness of the amount tendered to pay for the consumer’s expenses, not on whether the tender matches or exceeds the consumer’s claimed expenses.
Relators further argue that even if Plaintiffs’ belated notices were proper, the trial court abused its discretion by refusing to order the case abated for sixty days. For those DTPA claims controlled by the current DTPA, the trial court did not need to formally abate the suit because by the time it issued its ruling, more than sixty days had passed since Plaintiffs sent their notices. Under section 17.505, “[a] suit is automatically abated without the order of the court beginning on the 11th day after the date a [verified and uncontroverted] plea in abatement is filed” and continuing “until the 60th day after the date the written notice is served in compliance with Subsection (a).” Tex. Bus. & Comm.Code § 17.505(d), (e). Therefore, with respect to those claims that had already been automatically abated, the trial court did not need to formally grant another sixty-day abatement.
Relators assert, however, that the claims of one of the named plaintiffs, Envo-Tech, Inc., were not automatically abated because they were governed by the pre-1995 version of the DTPA. Envo-Tech purchased vehicles from Relators on October 17,1994, and April 26,1995, before the automatic abatement provisions became effective. Before the 1995 amendments, the DTPA did not specify the consequences for noncompliance with the notice requirement. In Hines v. Hash, 843 S.W.2d 464, 469 (Tex.1992), we. held that “if a plaintiff files an action for damages under the DTPA without first giving the required notice, and a defendant timely requests an abatement, the trial court must abate the [179]*179proceedings for 60 days.” Relators insist, therefore, that under the pre-1995 DTPA, the trial court was required to formally abate the proceedings for sixty days.
Which DTPA version applies to Envo-Tech’s claims, however, depends on the date the claims accrued. Suits filed before September 1, 1996, relating to claims accruing before September 1, 1995, are governed by the law in effect before the 1995 amendments. See Act of May 17, 1995, 74 th Leg., R.S., ch. 414, § 20, 1995 Tex. Gen. Laws 2988, 3004. A DTPA claim accrues when “the consumer discovered or in the exercise of reasonable diligence should have discovered the occurrence of the false, misleading, or deceptive act or practice.” Tex. Bus. & Comm.Code § 17.565. Relying on this statutory accrual rule, Envo-Teeh alleges that its claims accrued not when it paid the challenged tax, but rather when it discovered the alleged deceptive act. Because the parties dispute when Envo-Teeh’s claims accrued, we cannot conclude that the trial court’s refusal to order abatement was an abuse of discretion. See West v. Solito, 568 S.W.2d 240, 245 (Tex.1978) (“[A]n appellate court may not deal with disputed areas of fact in a mandamus proceeding.”).
Plaintiffs’ DTPA notices were adequate, and Relators have had several months to make a settlement offer since receiving them. Therefore, Relators have not established their right to relief by mandamus on the abatement issue.
Ill
Bifurcation of Discovery
The other issue in this mandamus proceeding involves discovery. Plaintiffs sent Relators interrogatories and document requests demanding disclosure of a broad range of information. Most of the proposed discovery can be broken down into four general categories: (1) each dealership’s full name, “dealer’s general distinguishing number,” any business aliases or physical addresses used and the periods of such use since January 1, 1994, and any automobile trade association memberships and the periods of such memberships since January 1,1992; (2) every oral and written communication with any purchasers, officers, salespersons, sales managers, finance and insurance workers, and automobile trade associations, regarding the vehicle inventory tax and any transaction in which it was charged; (3) identification of all persons having knowledge of relevant facts and what knowledge they may have; and (4) identification of the statutory or regulatory basis of any contention that the dealer is authorized to collect the vehicle inventory tax from the purchaser. Plaintiffs withdrew interrogatories that sought disclosure of each dealership’s net worth and financial statements.
Relators refused to answer any of the interrogatories, objecting that before the trial court ruled on various threshold issues — such as venue, jurisdiction, abatement, special exceptions, and class certification — discovery was premature, unduly burdensome, and constituted harassment. Relators also moved for a protective order to abate all discovery on the merits until at least thirty days after class determination. Relators argued that a bifurcation order would expedite class determination, protect Relators from discovery that would be rendered unnecessary if class status were denied, prevent the use of burdensome discovery to extort an unwarranted settlement, and promote judicial economy: “In summary, i) Plaintiffs’ initial written discovery is premature and ii) ... if unabated, will result in incalculable expense and hardship on, as well as unavoidable and unnecessary harassment of Moving Defendants.”
Plaintiffs opposed the motion and objections, arguing that such routine questions as “state your name” and “state your address” would help organize the pleadings and parties for purposes of the certification process. Plaintiffs contended that interrogatories seeking disclosure of inventory-tax-related communications are [180]*180necessary to help determine the size and identity of the putative class and to establish prima-facie proof of concerted action and conspiracy.
The trial court considered both Relators’ objections and their motion for protective order at a hearing. The trial court first issued an order denying Relators’ motion for protective order. Later the trial court issued a separate order overruling in part and sustaining in part Relators’ general and specific interrogatory objections. We emphasize, as Relators did throughout their ^briefing before this Court, that in this mandamus proceeding, Relators challenge only the trial court’s denial of their motion for protective order. They do not contest the trial court’s rulings on their overbreadth and other specific objections to Plaintiffs’ discovery requests. Relators contend that as a matter of law, they are entitled to an order bifurcating class and merits discovery.
A
We begin our analysis by reviewing some basic discovery principles. The primary objective of discovery is to ensure that lawsuits are “decided by what the facts reveal, not by what facts are concealed.” Jampole v. Touchy, 673 S.W.2d 569, 573 (Tex.1984). As the United States Supreme Court has noted, modern discovery and pretrial procedures serve the useful purpose of “[making] a trial less a game of blindman’s bluff and more a fair contest with the basic issues and facts disclosed to the fullest practicable extent.” United States v. Procter & Gamble Co., 356 U.S. 677, 682, 78 S.Ct. 983, 2 L.Ed.2d 1077 (1958).
In practice, however, discovery is not only “a tool for uncovering facts essential to accurate adjudication,” but also “a weapon capable of imposing large and unjustifiable costs on one’s adversary.” Frank H. Easterbrook, Comment, Discovery as Abuse, 69 B.U.L.Rev. 635, 636 (1989). Discovery is often the most significant cost of litigation. See Wayne D. Brazil, Views From the Front Lines: Observations by Chicago Lawyers About the System of Civil Discovery, 1980 AM. B. Found. Res. J. 219, 229. Because the costs of compliance are usually borne solely by the replying party, a requesting party improves its bargaining position by maximizing those costs. See Easterbrook, supra, at 636 (“Litigants with weak cases have little use for bringing the facts to light and every reason to heap costs on the adverse party.... The prospect of these higher costs leads the other side to settle on favorable terms.”). Both multiparty and class litigation can dramatically magnify those costs by expanding the scope of discovery. See CSR, Ltd. v. Link, 925 S.W.2d 591, 598 (Tex.1996) (Gonzalez, J., concurring) (recognizing that the costs of multi-party litigation can drive defendants to settle regardless of the merits); 7B ChaRles Alan Wright & Arthur R. Miller, Federal Practice and Procedure § 1796.1 (2nd ed.1986) (noting need, in class actions, to protect both absent class members and named representatives from harassing discovery). Recognizing the potential for these and other abuses, this Court and others have articulated principles and adopted procedural devices to curb discovery abuse.
First, discovery requests must be reasonably tailored to include only matters relevant to the case. See In re American Optical Corp., 988 S.W.2d 711, 712 (Tex.1998); Texaco, Inc. v. Sanderson, 898 S.W.2d 813, 814 (Tex.1995).1 Second, [181]*181discovery may not be used as a fishing expedition or to impose unreasonable discovery expenses on the opposing party. See K Mart Corp. v. Sanderson, 937 S.W.2d 429, 431 (Tex.1996); In re Time Warner Inc. Sec. Litig., 9 F.3d 259, 263 (2d Cir. 1993). Third, a court may “in the interest of justice,” issue a protective order to “protect the movant from undue burden, unnecessary expense, harassment, annoyance, or invasion of personal, constitutional, or property rights.” Tex.R. Civ. P. 192.6(b). The new discovery rules explicitly encourage trial courts to limit discovery when “the burden or expense of the proposed discovery outweighs its likely benefit, taking into account the needs of the case, the amount in controversy, the parties’ resources, the importance of the issues at stake in the litigation, and the importance of the proposed discovery in resolving the issues.” Tex.R. Civ. P. 192.4(b). Although a trial court has broad discretion to schedule and define the scope of discovery, it can abuse its discretion by acting unreasonably. See In re Colonial Pipeline Co., 968 S.W.2d 938, 941 (Tex.1998). A party resisting discovery, however, cannot simply make conclusory allegations that the requested discovery is unduly burdensome or unnecessarily harassing. The party must produce some evidence supporting its request for a protective order. See Garcia v. Peeples, 734 S.W.2d 343, 345 (Tex.1987); Independent Insulating Glass/Southwest, Inc. v. Street, 722 S.W.2d 798, 802 (Tex.App. — Fort Worth 1987, writ dism’d).
Other principles inform more specific situations. For example, courts may limit discovery pending resolution of threshold issues like venue, jurisdiction, forum non conveniens, and official immunity. See Tex.R. Civ. P. 190.4(b)(2) (contemplating that a Level 3 discovery control plan may phase discovery to resolve discrete issues); see, e.g., USX Corp. v. West, 759 S.W.2d 764, 767 (Tex.App. — Houston [1st Dist.] 1988, orig. proceeding) (special appearance).
Likewise, courts often limit discovery pending class determination. See, e.g., Washington v. Brown & Williamson Tobacco Corp., 959 F.2d 1566, 1570-71 (11th Cir.1992); Stewart v. Winter, 669 F.2d 328, 331-32 (5th Cir.1982); see also Rodriguez v. Banco Central, 102 F.R.D. 897, 903 (D.P.R.1984); National Org. for Women v. Sperry Rand Corp., 88 F.R.D. 272, 277 (D.Conn.1980). These limitations protect not only class-action defendants but also putative class-action plaintiffs from abusive discovery. See Eggleston v. Chicago Journeymen Plumbers’ Local Union No. 130, 657 F.2d 890, 895 (7 th Cir.1981); 7B Charles AlaN Weight, Arthur R. Miller & Mary Kay Kane, Federal Practice and Procedure § 1796.1 (2d ed.1986). Generally, however, a litigant will need some discovery to effectively support or oppose a class-certification motion. See Stewart, 669 F.2d at 331; Chateau de Ville Prods., Inc. v. Tams-Witmark Music Library, Inc., 586 F.2d 962, 966 (2d Cir.1978). [182]*182Some courts, in fact, have held that denial of discovery critical to class-determination issues is reversible error. See, e.g., In re American Med. Sys., Inc., 75 F.3d 1069, 1086 (6th Cir.1996); Duke v. University of Tex. at El Paso, 729 F.2d 994, 997 (5th Cir.1984); Chateau de Ville, 586 F.2d at 966; Doninger v. Pacific Northwest Bell, Inc., 564 F.2d 1304, 1312 (9 th Cir.1977); Dillon v. Bay City Constr. Co., 512 F.2d 801, 804 (5 th Cir.1975); Yaffe v. Powers, 454 F.2d 1362, 1366 (1st Cir.1972).
The amount and nature of discovery needed for class determination is case specific and depends on the claims and defenses being made. In some cases, the certification decision can be made primarily on the basis of the pleadings, postponing and potentially eliminating the need for elasswide discovery. See, e.g., Commercial Travelers Life Ins. Co. v. Spears, 484 S.W.2d 577, 579 (Tex.1972) (holding that the trial court abused its discretion by ordering discovery of other potential name plaintiffs when plaintiffs pleadings and evidence could not support a class action); Wente v. Georgia-Pacific Corp., 712 S.W.2d 253, 258-59 (Tex.App. — Austin 1986, no writ) (holding that when different laws applied to defendant’s transactions with various putative class members, precluding plaintiff from establishing a common question of law or fact among the putative class, plaintiff was not entitled to additional classwide discovery); Stewart, 669 F.2d at 332 (holding that certification decision on putative class of inmates in the jails of eighty-two different counties could be made on the basis of the pleadings). In many cases, however, discovery is needed to establish commonality of issues, typicality of claims, or predominance of common questions of law or fact over individual questions. Such discovery will frequently be enmeshed with the merits. See Coopers & Lybrand v. Livesay, 437 U.S. 463, 469, 98 S.Ct. 2454, 57 L.Ed.2d 351 (1978); see also David Crump, What Really Happens During Class Certification? A Primer for the First-Time Defense Attorney, 10 Rev. Litig. 1, 7 (1990) (“[S]uch issues as commonality, typicality, superiority, and predominance are at least tangentially related to the merits; i.e., one cannot know whether a representative’s claim is ‘typical’ of those of the class without knowing something about the merits.”).
Generally, it is within the trial court’s discretion to schedule discovery and decide whether and how much discovery is warranted to determine any certification questions. See In re Colonial Pipeline Co., 968 S.W.2d at 943. Factors in determining the scope of precertification discovery include the importance, benefit, burden, expense, and time needed to produce the proposed discovery. See Tex.R. Civ. P. 192.4; see also Kamm v. California City Dev. Co., 509 F.2d 205, 210 (9th Cir. 1975). Other factors include whether the individual claims are large enough to be worth pursuing if the class is not certified, and if so, whether the proposed discovery would relate to those individual claims. See Duke, 729 F.2d at 997; General Motors Corp. v. City of New York, 501 F.2d 639, 646 (2d Cir.1974).
B
With these general principles in mind, we address Relators’ contention that they are entitled, as a matter of law, to an order bifurcating class and merits discovery. Two considerations inform this determination. First, because the propriety of bifurcating class and merits discovery is case specific, we evaluate whether Relators have shown that the specific claims and pleadings in this case are clearly separable; that is, can it be determined whether the requested discovery is relevant only to the merits and not to the certification issues, or whether the discovery is overly broad. Second, we evaluate whether Rela-tors established their right to bifurcation by showing that Plaintiffs’ proposed discovery is unduly burdensome or unnecessarily harassing.
Here, Relators failed to show or otherwise explain in their motion to bifur[183]*183cate that the class and merits issues are clearly separable. In this case, class and merits discovery are likely to be intertwined because the Plaintiffs allege oral and written misrepresentations that vary from one class member to another. Plaintiffs’ pleadings indicate that different dealerships have characterized the “add-on” charge that forms the basis of this suit differently. One dealership characterized it as a “value tax,” another as an “inventory tax,” another as a “vehicle inventory tax,” and still another as a “dealer’s inventory tax.” These characterizations are material to the claim that the dealerships misrepresented what is in fact a property tax the state charges dealerships as a transactional tax the state charges consumers. Because whether a fraud was committed may depend on how the add-on charge was characterized, the variations in those characterizations may undermine the requisite commonality and typicality needed for class certification. See Simon v. Merrill Lynch, Pierce, Fenner & Smith, Inc., 482 F.2d 880, 882 (5th Cir.1973); Life Ins. Co. v. Brister, 722 S.W.2d 764, 774 (Tex.App. — Fort Worth 1986, no writ). Classwide discovery may uncover further variations in those representations weighing against class certification. On the other hand, classwide discovery may uncover a common thread of deceit running through the dealerships’ various representations weighing in favor of class certification. See Adams v. Reagan, 791 S.W.2d 284, 291 (Tex.App. — Fort Worth 1990, no writ). Therefore, although such discovery would be relevant to the merits, we cannot say that Relators’ motion to bifurcate shows the discovery is not relevant to the certification issues as well.
Moreover, in this case, an order bifurcating class and merits discovery without specifically differentiating the two would serve no constructive purpose. See 5 James Wm. MooRE et al., Moore’s Federal PraCtioe 3d § 23.61[6][b] (3d ed. 1999) (“[BJecause class certification issues are not always completely separable from the merits of the class claims, bifurcation of discovery may sometimes be counterproductive.”). First, a nonspecific bifurcation order would likely precipitate nettlesome disputes about whether a particular interrogatory or document request pertains to certification or merits. See, e.g., Eggleston, 657 F.2d at 893 (illustrating the disputes that can follow an order limiting initial discovery to class-determination issues). Second, such an order could unreasonably interfere with discovery of facts essential to class determination.
Relators’ motion for protective order insisted that the trial court abate all merits discovery until thirty days after it determined the class. The supporting brief never specifically differentiated class and merits discovery. Moreover, the brief did not give the trial court any practical guidance on how it should make that distinction or efficiently implement the proposed order. Relators’ most recent bifurcation proposal, offered to the Plaintiffs as a compromise, is no more specific:
Prior to certification, parties may obtain discovery regarding any matter that is reasonably calculated to lead to the discovery of admissible evidence relevant to class certification. Evidence that relates primarily to the proof of liability and damages shall not be discoverable.
If the trial court were to implement Rela-tors’ most recent bifurcation proposal, the parties would inevitably dispute whether each interrogatory and document request relates “primarily” to the merits or to class certification. Indeed, Relators’ briefs insist that all of Plaintiffs’ interrogatories' — ■ including some as simple as “state your full name” or “state your address” — -are “either exclusively or primarily relevant to liability and damages, not certification.” Relators’ proposed bifurcation order, therefore, would accomplish nothing. The trial court would still have to rule on the propriety of each contested discovery request — which, in this case, means each and every interrogatory and document request.
[184]*184Also, Relators’ proposed bifurcation order could prevent Plaintiffs from obtaining facts essential to class determination. One commentator suggests that a defendant’s “best strategy may be to resist merits discovery while at the same time arguing that plaintiffs have not shown typicality or commonality, which depend somewhat on the merits.” See Crump, supra at 7. There are, in fact, hints of such a strategy in Relators’ briefs. On the one hand, Re-lators argue that before class determination, Plaintiffs are not entitled to discover the various representations the dealerships made to their customers in passing on the dealer inventory tax. On the other hand, Relators suggest that they will challenge certification on the ground that “the claims depend on oral statements that are case specific and each plaintiff is required to present proof of reliance.” An order abating all merits discovery could prevent Plaintiffs from showing a common thread of deceit in Relators’ various representations or other elements of commonality and typicality, potentially defeating certification.
Moreover, Relators faded to support their complaints of burdensomeness and harassment with anything more than general allegations. Without some more detailed explanation and proof, Relators have simply not met the basic requirements for limiting the scope of discovery under the rules of civil procedure. See Tex.R. Civ. P. 192.4,192.6.
By contrast, a specific discovery order— one directly addressing the amount and nature of discovery needed — would provide a more practical and efficient mechanism for limiting precertification discovery than a blanket bifurcation order. When disputes arise about the scope of precertification discovery, the Manual for Complex Litigation suggests that the parties present a specific discovery plan that identifies the contemplated discovery and the subject matter to which it relates:
Bifurcating class and merits discovery can at times be more efficient and economical (particularly when the merits discovery would not be used if certification were denied), but can result in duplication and unnecessary disputes among counsel over the scope of discovery. To avoid this, the court should call for a specific discovery plan from the parties, identifying the depositions and other discovery contemplated and the subject matter to be covered. Discovery relating to class issues may overlap substantially with merits discovery. A key question in class certification may be the similarity or dissimilarity between the claims of the representative parties and those of the class members — an inquiry that may require discovery on the merits and development of basic issues.
Manual for Complex LitigatioN, Third, § 30.12 (1995). Another commentator, writing for the defense bar, explains the need for meaningful discovery limitations:
Divergent views concerning the propriety of what traditionally is understood as “bifurcation” should be understood to arise from the problem of the distinction between class and merits discovery that defense counsel have typically sought to draw, rather than from any broader notion that all discovery should proceed at once. Accordingly, litigants should always be looking for other distinctions on the basis of which discovery can be segmented to control burden.
Timothy K. Beeken, Class Action Discovery: The Defense’s Burden, Address at the Meeting of the National Institute on Class Actions: Section of Litigation (June 12, 1998), available in Westlaw, N98CACB ABA-LGLED D-l. Beeken suggests that production obligations be sequenced or phased, postponing production of the most sweeping discovery requests until after the most obviously pertinent sources of information are produced. See id. As with all litigants, we expect class-action litigants to cooperate on discovery plans and make any agreements reasonably necessary for the efficient disposition of the case. See Tex.R. Civ. P. 191.2.
[185]*185In this case, Relators urge that they are entitled, as a matter of law, to abate all merits discovery or all discovery that relates primarily to proof of liability or damages. Under the circumstances, they are not. Here, the merits and class issues are intertwined. Relators did not give the trial court or this Court any guidance on how to distinguish merits and certification discovery, much less how to evaluate to what issue the challenged discovery “primarily” relates. The relief sought in Relators’ motion for protective order, abating of all Plaintiffs’ discovery requests, would not give Plaintiffs or the trial court a fair factual sketch of matters related to certification. See Sirota v. Solitron Devices, Inc., 673 F.2d 566, 571-72 (2d Cir.1982) (“In making a certification decision, a judge must look somewhere ‘between the pleadings and the fruits of discovery.... [E]nough must be laid bare to let the judge survey the factual scene on a kind of sketchy relief map, leaving for later review the myriad of details that cover the terrain.’”) (quoting Professional Adjusting Sys. of Am., Inc. v. General Adjustment Bureau, Inc., 64 F.R.D. 35, 38 (S.D.N.Y. 1974)). Rather, Relators’ motion failed to clearly identify the specific matters and discovery requests that they contend are irrelevant or overbroad in relation to any threshold issues and explain the basis for those contentions. Finally, Relators did not produce any evidence that their existing discovery obligations are unduly burdensome, but argued only in the most general terms that all merits discovery should be abated until a decision on certification. It is not an abuse of discretion for a trial court to deny a motion for protective order that does not specifically identify the discovery to be limited, or that proposes to overly restrict relevant discovery. On this record, we hold that the denial of Relators’ motion for protective order was not an abuse of discretion. See In re Colonial Pipeline Co., 968 S.W.2d at 941.
IV
Conclusion
For the above reasons, we conclude that the Relators have not established their right to relief by mandamus on either the abatement issue or the discovery matter. Therefore, we deny the writ of mandamus.
Justice HECHT filed an opinion concurring in part and dissenting in part, in which Justice OWEN joined.