Hello Raul,
the command should change the STP mode to IBM compatible instead of IEEE 802.1D.
when the command has been configured IBM switches or other vendor switches running IBM STP instead of 802.1D were connected to the CATOS switch.
The CATOS swich might have had installed a token ring module for example.
On Token Ring the switches use source route bridging instead of transparent bridging.
It was a totally different way to switch traffic that has been overcomed by ethernet developements
see
http://books.google.it/books?id=of76QmGUnAoC&pg=PA645&lpg=PA645&dq=IBM+STP+and+802.1D&source=bl&ots=ncP7Ls3VRO&sig=XxcePq4FtKlOJtv5lAu9MWuWNLE&hl=it&sa=X&ei=-_uzT7SdDO334QTmncCADg&ved=0CHcQ6AEwCA#v=onepage&q=IBM%20STP%20and%20802.1D&f=false
The command can be removed or not depending on what is connected to the CATOS switch.If it is a bank and the switch is used to connect to an IBM mainframe you can bet that the command is still needed!
At the origins of STP in addition to 802.1D there were also a DEC STP and an IBM STP.modern IOS switches support only standard based 802.1D or other more modern standards like MST 802.1s.
Hope to help
Giuseppe
