Field help (COMTEXCTA) 

Use this field to add comments to this record. This is a free-format narrative field. The comments should be specific to this record. They should do more than just "describe" this record.

As task categories are used for consolidating expenses against a particular project you might use this field to explain the structure of the category code. It might also serve to provide a facility for listing category types acceptable for individual project codes or customers, for example.