Unfortunately, the overlay technique, though common, is not an efficient method for the creation of hotspots. In electronic catalogs that require frequent revisions, this technique often demands a lot of manual effort during each revision.

This is due to the technical approach of the overlays. Overlays live in their “own“ world, which is only connected to the rest of the catalog through manual work. When the contents of the catalog are changed, the overlays often become useless because the hotspots located on them direct to nothing. The disadvantage is clear: hotspots and corresponding links are not thoroughly connected with the contents of the catalog. 

The problems resulting from this disadvantage can be compared with those that occurred with the creation of indices before programs automated this function.It is the case that a minor change of content on one page sometimes resulted in a page break, meaning that all subsequent index references had to be check and realigned.