+ ones (default: empty).
+
+- **`FINDFILTERONLY`:**
+ A semicolon‐separated list of regular expressions, at least one of
+ which the paths for sources and includes are required to match,
+ unless empty (default: empty).
+
+- **`FINDFILTEROUT`:**
+ A semicolon‐separated list of regular expressions, each of which
+ matches paths that should _not_ be considered sources or includes
+ (default: empty).
+
+- **`FINDINCLUDEFILTERONLY`:**
+ A semicolon‐separated list of regular expressions, at least one of
+ which the paths for includes are required to match, unless empty
+ (default: empty).
+
+ Note that only paths which already match `FINDFILTERONLY` are
+ considered.
+
+- **`FINDINCLUDEFILTEROUT`:**
+ A semicolon‐separated list of regular expressions, each of which
+ matches paths that should _not_ be considered includes, but may
+ still be considered sources (default: empty).
+
+- **`FINDFILTERONLYEXTENDED`:**
+ If non·empty, `FINDFILTERONLY` is an extended regular expression;
+ otherwise, it is basic (default: empty).
+
+- **`FINDFILTEROUTEXTENDED`:**
+ If non·empty, `FINDFILTEROUT` is an extended regular expression;
+ otherwise, it is basic (default: matches `FINDFILTERONLYEXTENDED`).
+
+- **`FINDINCLUDEFILTERONLYEXTENDED`:**
+ If non·empty, `FINDINCLUDEFILTERONLY` is an extended regular
+ expression; otherwise, it is basic (default: matches
+ `FINDFILTERONLYEXTENDED`).
+
+- **`FINDINCLUDEFILTEROUTEXTENDED`:**
+ If non·empty, `FINDINCLUDEFILTEROUT` is an extended regular
+ expression; otherwise, it is basic (default: `1` if either
+ `FINDFILTEROUTEXTENDED` or `FINDINCLUDEFILTERONLYEXTENDED` is
+ non·empty).