Maryland Commercial Law Section 22-207

      (a)      A release is effective without consideration if it is:

            (1)      In a record to which the releasing party agrees, such as by manifesting assent, and which identifies the informational rights released; or

            (2)      Enforceable under estoppel, implied license, or other law.

      (b)      A release continues for the duration of the informational rights released if the release does not specify its duration and does not require affirmative performance after the grant of the release by:

            (1)      The party granting the release; or

            (2)      The party receiving the release, except for relatively insignificant acts.

      (c)      In cases not governed by subsection (b) of this section, the duration of a release is governed by § 22-308 of this title.