This variable contains the output nesting level. When its '1', the output goes to the default output file, each #Output with filename adds one while a #output without file subtracts one.
This variable would be handy in complex macro sets where #output commands are automatically generated.
This is a Standard Definition which always exists (you don't need to #define it). Note that you can create your own variations or completely new ones (see the examples).
This line is at Output Level 1
#output '2nd'
This line is at Output Level 2
#output 'c<$colon>\path\3nd.ext' AsIs
This line is at Output Level 3
#output
This line is at Output Level 2
#output
This line is at Output Level 1