Harpist was the continuation of the European project EuroBus/Transmodel analysing the needs expressed by a range of European projects as regards the Public Transport data.

Harpist extended Transmodel and made it possible to validate Transmodel at a European level. The result of the validation by a large panel of European experts was Transmodel V4, published in July 1995. This version was then submitted to the European standardisation body CEN TC278 WG3 for comments.

The CEN comments were then processed and within the European project Titan, Transmodel version V.4.1.1. was issued and submitted to CEN TC278 for a vote.