During the development phases of heat source programs (the fabrication for design verification, engineering evaluation, etc.), heat sources and test capsules are often required prior to the formalization of specifications and drawings. Furthermore, there are also programs where the quantities and technology are such that a detailed and unique set of documentation is not justified. Consequently, this document is intended to be a general guide to the criteria applicable in evaluating the acceptability of radioisotopic heat sources and test capsules when they are produced under these circunnstances. The guidelines are general in nature, since many applications of heat sources have unique requirements, but typical values are given where practicable. This document is written in the format of a general specification to enhance its usefulness. (auth)