A local variable in M refers to a variable used solely within the scope of a single process. Local variable names have no leading delimiter.

M makes a local variable available and subject to modification by all routines executed within a process from the time that variable is first SET until it is KILLed, or until the process stops executing M. However, M "protects" a local variable after that variable appears as an argument to a NEW command, or after it appears as an element in a formalist used in parameter passing. When M protects a local variable, it saves a copy of the variable's value and makes that variable undefined. M restores the variable to its saved value during execution of the QUIT that terminates the process stack level associated with the "protecting" NEW or formalist. For more information on NEW and QUIT, refer to the "Commands" chapter in this manual.

M restricts the following uses of variables to local variables: