Hawaii Rules of Penal Procedure (HRPP) Rule 40 provides, in relevant part, as follows: (a) Proceedings and Grounds. the post-conviction proceeding established by this rule shall encompass all common law and statutory procedures for the same purpose, including habeas corpus and coram nobis; provided that the foregoing shall not be construed to limit the availability of remedies in the trial court or on direct appeal. Said proceeding shall be applicable to judgments of conviction and to custody based on judgments of conviction, as follows: (1) from Judgment. at any time but not prior to final judgment, any person may seek relief under the procedure set forth in this rule from the judgment of conviction, on the following grounds: (i) that the judgment was obtained or sentence imposed in violation of the constitution of the United States or of the State of Hawaii; (ii) that the court which rendered the judgment was without jurisdiction over the person or the subject matter; (iii) that the sentence is illegal; (iv) that there is newly discovered evidence; or (v) any ground which is a basis for collateral attack on the judgment. (2) from Custody. Any person may seek relief under the procedure set forth in this rule from custody based upon a judgment of conviction, on the following grounds: (i) that sentence was fully served; (ii) that parole or probation was unlawfully revoked; or (iii) any other ground making the custody, though not the judgment, illegal. (3) Inapplicability. Rule 40 proceedings shall not be available and relief thereunder shall not be granted where the issues sought to be raised have been previously ruled upon or were waived. An issue is waived if the petitioner knowingly and understandingly failed to raise it and it could have been raised before the trial, at the trial, on appeal, in a habeas corpus proceeding or any other proceeding actually conducted, or in a prior proceeding actually initiated under this rule, and the petitioner is unable to prove the existence of extraordinary circumstances to justify the petitioner's failure to raise the issue. There is a rebuttable presumption that a failure to appeal a ruling or to raise an issue is a knowing and understanding failure.