Appellants made oral in-custody statements which were reduced to typewritten form. Each typed statement was preceded by a preamble reciting warnings which did not in all respects comply with Miranda. At trial a government agent was allowed to testify to oral warnings which were given before any statements were made and which did meet Miranda requirements.

Appellants do not say that the oral warnings did not meet Miranda standards but that such use of oral testimony is forbidden by the parol evidence rule. The purpose of the Miranda prin[*222] ciple is to guarantee the accused knowledge of basic constitutional entitlements, and the giving of required warnings communicating such knowledge is unrelated to the consensual contractual problems of commercial law to which the parol evidence rule relates.

Perhaps appellants’ contention could be more aptly phrased as questioning whether where an agent has obtained the signature of the accused to a written acknowledgement of warnings the agent may supplement the written statement by oral testimony which supplies essential missing elements. Such procedure violates no constitutional right; it presents only credibility issues, and we are shown no reasons for overturning the trial court’s acceptance of the agent’s oral recital of the warnings he gave.

Contentions concerning remarks made by the Deputy United States Marshal to the jury are totally without merit.

Affirmed.