&& => && for convenience in shell runes
&\& => & general escaping mechanism
-&\$ => $
+&\$ => $ provided for $-doubling regimes
&\NEWLINE eats the newline and vanishes
&$VARIABLE => $(sub_dir_VARIABLE) or $(TOP_VARIABLE)
`all' is extra special: every directory has an `all'
target, which corresponds to &TARGETS.
+
+Dollar doubling and macro assistance
+------------------------------------
+
+&$+ Starts dollar-doubling
+&$- Stops dollar-doubling
+ Both are idempotent and local to the file or context.
+
+While dollar-doubling:
+- - - - - - - - - - -
+
+$ => $$ including $'s produced by other
+ &-expansions not mentioned here
+
+&\$ => $
+&$NN => $(NN) where N are digits
+&$( => $(
+
+
Subdirectory and variable naming
--------------------------------