The criterion that has been followed to create a standard category model for e-TRAM is that defined in the section of "Vocabulary of common functions of local administration", which includes 59 categories that will be mandatory to report at the level of the Administrative Information System (SIA) .
More information about the Administrative Information System (SIA) at the following link:
https://administracionelectronica.gob.es/ctt/sia/descargas#.ZHcT5nbP2Ul
And specifically, the documentation has a spreadsheet with the details of the different categories. At level e-TRAM we have the 59 that are part of the first level:
Based on this document, at e-TRAM we have 59 categories to classify all the procedures we offer, both those available to be incorporated into the catalog (about sixty), and your own procedures that you can parameterize using the “ own procedures ” functionality.