INTEROPERABILITY FOR SPECIALIZED SOFTWARE
Specialized software presents a lot of reusability problems. For some examples, look at the references to system requirements for Chime (Martz, 2002), WebEQ (Design Science, 2004) and TI-Navigator (TI, 2004). Applications with small markets are rarely as well-supported as standard applications (such as spreadsheets and word processors) and often are developed for only one platform. It is best to stay away from content that is written in a proprietary format that can only be understood by a non-standard tool.
It should be noted that some communities have developed formats such as TEX and MathML that are far from standards in the world at large but that are widely supported within a given community of practice and can safely be used, with the understanding that doing so will limit reusability outside of the community in question.