If you explicitly create or modify one of the symbols, rather than
let IPCS create or modify it, you might bypass IPCS's validity checking
process. For example, if you create the symbol UCB000E with the following
subcommand:
equate ucb000e 4140.
and later use
the FINDUCB subcommand to locate the UCB for device 000E, the FINDUCB
subcommand finds the symbol in the symbol table and displays the storage
at the address associated with that symbol. Because your EQUATE subcommand
did not specify STRUCTURE(UCB), the storage at X‘4140’ was not validity
checked to ensure that it is a UCB.