The State of Maine appeals from a judgment entered in the Superior Court (Cumberland County, Fritzsche, J.) in a post-conviction review proceeding1 that allowed Bruce D. Wellman, the petitioner, to withdraw his guilty pleas upon which his convictions were based. Wellman cross-appeals based on the State’s alleged procedural default.
In 1985, pursuant to the Interstate Compact on Detainers, 34-A M.R.S.A. §§ 9601-*11799636 (1988), Wellman, while serving a New Hampshire prison sentence, was brought to Maine to be tried for crimes of burglary, theft and robbery, for which he had been indicted in eight different Maine counties. In September 1986, following discussions with prosecutors and pursuant to a plea agreement, Wellman entered pleas of guilty to thirty-four different counts of burglary, theft and robbery, arising from charges in Cumberland, Knox, Lincoln and Sagadahoc Counties.2 At the time of the pleas, he was still in execution of his New Hampshire sentence but was being held in the Cumberland County Jail. He was discharged from the New Hampshire sentence in November 1986, but remained at the Cumberland County Jail awaiting sentencing in his Maine cases. In April 1987, the Superior Court (Lipez, J.) in conformity with the plea agreement sentenced Well-man to twenty years’ imprisonment, with all but nine years suspended, followed by three years of probation.
Wellman initially was given pretrial detention credit toward his sentence for the entire time he spent in the Cumberland County Jail before sentence was imposed. Subsequently, the Maine State Prison, noting that Wellman was in execution of a New Hampshire sentence for most of the time he was in Maine awaiting trial, recalculated his sentence pursuant to 17-A M.R. S.A. § 1253(2) (Supp.1990),3 crediting him with 140 days rather than the previously credited 686 days for pretrial detention.4
Wellman filed a petition for post-conviction review, later amended, alleging that the failure to credit him with all the time spent in the Cumberland County Jail violated the terms of his plea agreement, that the plea agreement could not be complied with, and that the State had given him false information about the terms of a plea agreement the State made with one of Wellman’s co-defendants who was a potential prosecution witness against Wellman.5 The State’s answer to the petition was not filed within twenty days after notice that the amended petition had been filed, but the Superior Court (McKinley, J.) subsequently granted the State’s motion for additional time in which to answer the petition.
After a testimonial hearing on Wellman’s post-conviction petition, the court found that at the time of the plea agreement, Wellman subjectively expected that his sentence would be fully credited for all pretrial time spent incarcerated in Maine, and that his subjective belief was objectively reasonable. The court concluded that even though Wellman’s expectation was “neither legally correct6 nor part of the plea agreement ...,” the pleas were involuntary and *1180allowed Wellman to withdraw them. The State has appealed the court’s order, and Wellman has cross-appealed the court’s granting of the State’s motion for extension of time within which to file an answer.
Wellman’s Cross-appeal
In his cross-appeal, Wellman contends that we should not reach the substantive merits of the State’s appeal because the court failed to default the State and erroneously granted its motion to extend the time within which to answer his petition. We disagree.
Post-conviction proceedings frequently are filed pro se. Often the petitions have to be amended for cognizable grounds for relief to be properly alleged and to insure that all legitimate grounds for relief are stated. Any grounds for relief that can be raised but are not raised in the petition are deemed waived and cannot be raised in subsequent petitions. 15 M.R.S.A. § 2128(3); McEachern v. State, 456 A.2d 886, 889 (Me.1983). Responses from the State are required so that the issues in dispute may be identified. The response may be in the form of an answer, a motion to dismiss, or a notice that the State does not contest the petition, see M.R.Crim.P. 71, and need not be filed until ordered by the court, or until the petition is amended or there is a notification that no amended petition is to be filed. M.R.Crim.P. 70(c)(1) & (2). Rule 70(c) provides that the State must respond to the petition within twenty days of receipt of a copy of the order, the amended petition, or the notification that no amended petition is to be filed. Pursuant to M.R.Crim.P. 45(b) and 71, the time to respond to the petition may be enlarged after the expiration of the twenty-day response period, upon a showing of excusable neglect.7
Unlike other rules governing timeliness in civil cases, see, e.g., M.R.Civ.P. 8(d), 12(h), 55, there are no express provisions for defaulting the State in a post-conviction proceeding. Indeed, it is in the interest of the public and helpful to the court for the State to be an active participant in post-conviction proceedings. Although the State may be subject to default and precluded from contesting the allegations in a post-conviction petition on the basis of timeliness, such defaults are not automatic, but rather are subject to the sound discretion of the court. In this case, the court granted the State’s motion for an extension of time to file its response after a full hearing at which the reason for the State’s delay was disclosed.8 We discern no abuse of the court’s discretion in allowing the State to file a response.
State’s Appeal
In its appeal, the State does not dispute the factual findings made by the Superior Court. The State contends, however, that the court erred in concluding that Wellman’s understanding as to his entitlement to pretrial detention credit rendered his pleas involuntary. Because Well-man’s expectation was concerning a matter collateral to his sentence, was not a part of the plea agreement, and was not caused by any misrepresentation that it was part of the plea agreement, we agree with the State and vacate the judgment.
M.R.Crim.P. 11 requires the court, prior to acceptance of a guilty plea, to insure that the plea is made knowingly, that the plea is voluntary and that there is a factual basis for the charge.9 The court *1181fully complied with the requirements of Rule 11 at the time Wellman entered his guilty pleas. The court informed Wellman of the direct sentencing consequences of his pleas and later imposed a sentence consistent with the plea agreement. There is no requirement under Rule 11 that the court inform the defendant of each and every collateral consequence of his plea and the resulting sentence, such as where he is to be incarcerated, what good time credits he may be entitled to earn, or to what pretrial detention credit he may be entitled. See United States v. Bouthot, 878 F.2d 1506, 1511-12 (1st Cir.1989); United States v. Fernandez, 877 F.2d 1138, 1143 (2d Cir.1989); Hill v. Lockhart, 474 U.S. 52, 56, 106 S.Ct. 366, 369, 88 L.Ed.2d 203 (1985).
A plea is voluntary if it is “the product of a defendant’s free choice and not the result of force, threats or promises other than those in connection with a plea agreement.” M.R.Crim.P. 11(d). Wellman’s subjective belief as to his entitlement to credit for all the time he was incarcerated in Maine was the basis for the post-conviction court’s conclusion that his pleas were involuntary. That misunderstanding concerning credit for the entire time of his incarceration in Maine did “not result from force, threats or promises.” Moreover, credit for time served was not an explicit part of the plea agreement and Wellman’s expectation was not caused by any misrepresentation that it was part of the agreement. Cf. McAleney v. United States, 539 F.2d 282, 284 (1st Cir.1976) (guilty plea involuntary when defendant mistakenly told there was plea agreement).
The Superior Court erred in concluding that Wellman’s otherwise voluntary pleas were made involuntary by his subjective misunderstanding as to his entitlement to credit for pretrial detention in Maine, when that entitlement was not part of the plea agreement and was not induced by misrepresentation.
The entry is:
Judgment vacated. Remanded to Superi- or Court for denial of Petition for Post-conviction Review.
ROBERTS, WATHEN, GLASSMAN and BRODY, JJ., concur.
. See 15 M.R.S.A. §§ 2121-2132 (Supp.1990); M.R.Crim.P. 65-78.
. The charges were consolidated for purposes of the pleas. Wellman had other convictions, also based on guilty pleas, for offenses in Somerset, Franklin, Androscoggin and York Counties that are not at issue in this appeal.
. 17-A M.R.S.A. § 1253(2) reads in pertinent part:
2. Each person sentenced to imprisonment who has previously been detained for the conduct for which the sentence is imposed in any state correctional facility or county institution or facility or in any local lockup awaiting trial, during trial, post-trial awaiting sentencing or post-sentencing prior to the date on which the sentence commenced to run ... and not in execution of any other sentence of confinement, shall be entitled to receive a day-for-day deduction from the total term of imprisonment required under that sentence.
(Emphasis added.)
. Wellman does not dispute the correctness of the prison’s calculation of time, nor does he challenge the authority of the prison to recalculate his sentence. We note, however, that the sentencing court receives a statement of time of detention and makes it a part of the official record pursuant to 17-A M.R.S.A. § 1253(2) (Supp.1990). Any changes to the amount of detention time credited to a sentence must be sent to the clerk and become part of the official record.
. The Superior Court did not address the allegation pertaining to the plea agreement of the co-defendant in its decision granting Wellman’s post-conviction petition. We have examined the contention and conclude that Wellman has not alleged a sufficient nexus between his plea and that of the co-defendant to make the co-defendant’s case relevant to Wellman’s.
. Under 17-A M.R.S.A. § 1253(2), Wellman was not entitled to pretrial detention credit for the time spent in the Cumberland County Jail in execution of his New Hampshire sentence. See supra note 2.
. Prior to the twenty-day period, the court may extend the time for good cause shown. M.R. Crim.P. 45(b).
. The State was awaiting the preparation of a transcript, ordered by Wellman, from an earlier hearing on a motion filed by Wellman pursuant to M.R.Crim.P. 35 to correct or reduce his sentence. The State contended that some of the testimony at the hearing was crucial to a determination of whether the credit for pretrial detention was part of the plea agreement and would have affected the State's answer.
.M.R.Crim.P. 11(b) — Ce) provide:
(b) Prerequisites to Accepting a Plea of Guilty or Nolo Contendere to a Class C or Higher Crime. In all proceedings in which the offense charged is murder or a Class A, Class B, or Class C crime, before accepting a plea of guilty or nolo contendere, the court shall insure:
*1181(1) That the plea is made with knowledge of the matters set forth in subdivision (c); and (2) That the plea is voluntary within the meaning of subdivision (d); and
(3) That there is a factual basis for the charge, as provided in subdivision (e); and (4) That an unrepresented defendant has waived the defendant’s right to counsel.
(c)Insuring That the Flea is Made Knowingly. Before accepting a plea of guilty or nolo contendere, the court shall address the defendant personally in open court and inform the defendant of, and determine that the defendant understands, the following:
(1) The elements of the crime charged, the maximum possible sentence and any mandatory minimum sentence; and
(2) That by pleading guilty or nolo conten-dere the defendant is relinquishing the right to a trial, at which the defendant would have the following rights:
(A) The right to be considered innocent until proven guilty by the state beyond a reasonable doubt; and
(B) The right to a speedy and public trial by the court or by a jury; and
(C) The right to confront and cross-examine witnesses against the defendant; and
(D) The right to present witnesses on the defendant’s behalf and the right to either be or decline to be a witness on the defendant’s behalf.
(d) Insuring That the Plea is Voluntary. Before accepting a plea of guilty or nolo conten-dere, the court shall determine that the plea is the product of the defendant’s free choice and not the result of force, threats or promises other than those in connection with a plea agreement.
The court shall make this determination by addressing the defendant personally in open court.
The court shall inquire as to the existence and terms of a plea agreement, as provided in Rule 11 A.
(e) Insuring That There is a Factual Basis for the Plea. Before accepting a plea of guilty or nolo contendere, the court shall make such inquiry of the attorney for the state as shall satisfy it that the state has a factual basis for the charge.