//==============================================
File: tmp_macro_defaults2.txt

a_color=$(COLOR)
b_color=$(COLOR=green)
c_color=$(COLOR:=green)

a_name=$(NAME)
b_name=$(NAME=fred)
c_name=$(NAME:=fred)

//==============================================
File: hard_mind_beg.txt
Args: COLOR=red NAME= --lenient

#include tmp_macro_defaults2.txt

//----------------------------------------------
File: hard_mind_tar.txt

a_color=red
b_color=red
c_color=red

a_name=
b_name=
c_name=fred