SAP/Sybase has many a sub/helper procedures where logic is neatly packed so that it can be called from various places. Manuals may not explain about the the sub/helper procedure(s). e.g. sp_sysmon calls a number of procedures depending on options chosen. But you will find documentation about sp_sysmon mostly.
SAP/Sybase has ( so far !) not hidden the source SQL of most of the stored procedures either. So if you are curious you can look at the code using the technique Bret shows above.
So the source code above and the name of the procedure give you a hint of what is being done.
sp_depends for this procedure shows that it taps into configuration system tables and the proc itself is called by other system procedures like sp_dboption, sp_configure, sp_dropdevice etc...
HTH
Avinash