ASMMAI126E BREAKs may be cleared on this panel, but not changed

Explanation
 An attempt has been made to alter either the address,
commands, or conditions associated with a breakpoint or watchpoint
using typeover modification on the Break window. The only supported
typeover modification is the clearing of a breakpoint by overtyping
it with blanks.

User response
 Use the BREAK command to alter breakpoint address
or command values. Use the WATCH command to alter watchpoint address,
command, or condition values.