When a new category is selected in the descriptor category browser, the list of descriptors changes to show all descriptors already in that category. Browsing the set of existing descriptors can help choose which category a new descriptor should be added to.
Individual descriptors are assumed to be unambiguous, ie that they mean the same whoever uses them and whenever they use them. In practice this assumption turns out to be very nearly true, but some descriptors created by authors can be ambiguous. For example, the descriptor suspension can mean the action of suspending something (as in colposuspension) or a particular formulation of a drug (as in sugar-free suspension). The descriptor bladder could mean either the urinary bladder or the gallbladder.
A reasonable strategy is to prohibit the further use of such descriptor names once they are identified as ambiguous. This can be done by creating a new descriptor category (e.g. called BannedDescriptors) and placing all ambiguous descriptors in that category. The BannedDescriptors category itself is then flagged using the Hide category in SPET check box. This has the effect that users can neither select these descriptors for use in new expressions, nor add them (as they are already known to the system). The different meanings intended by the original ambiguous descriptor are then made available as more than one descriptor, for example bladder is banned but replaced with urinary bladder, gallbladder and bladder (urinary).