5.27 UNDEF

Undefine a register symbolic name.

The UNDEF directive is used to undefine a symbol previously defined with the DEF directive. This provides a way to obtain a simple scoping of register definitions, to avoid warnings about register reuse.

Syntax
.UNDEF symbol
Example
.DEF var1 = R16 
ldi var1, 0x20 
... ; do something more with var1 
.UNDEF var1 

.DEF var2 = R16 ; R16 can now be reused without warning.