- Rules to use with `find` when searching for source files (default:
- `-flags -nohidden -and -not -name '.*'`).
+ Rules to use with `find` when searching for source files.
+ The default ignores files that start with a period or hyphen‐minus
+ and those which contain a hash, buck, percent, asterisk, colon,
+ semi, eroteme, bracket, backslash, or pipe.
+
+- **`EXTRAFINDRULES`:**
+ The value of this variable is appended to `FINDRULES` by default, to
+ enable additional rules without overriding the existing ones.
+
+- **`FINDINCLUDERULES`:**
+ Rules to use with `find` when searching for includes (default:
+ `$(FINDRULES)`).
+
+- **`EXTRAFINDINCLUDERULES`:**
+ The value of this variable is appended to `FINDINCLUDERULES` by
+ default, to enable additional rules without overriding the existing
+ ones.