We present **Gemedoc**, a platform for text similarity annotation based on the spatial, the thematic, and ultimately the temporal dimensions. To this end, a two-step annotation protocol was designed to assess the similarity between two documents: (1) identification of salient features according to the two analysis dimensions; (2) similarity assessment according to a 4-degree scale. Ultimately, the labeled data retrieved from different corpora could be used as benchmark for text-mining applications.