Add EXTRA* variables

[Shushe] / README.markdown

diff --git a/README.markdown b/README.markdown
index 9d518896eaed97d4e8903bde4c9390a71c1deda3..654904ae9eda3ab787fbdc83dc7b001778f5ffda 100644 (file)
--- a/README.markdown
+++ b/README.markdown
@@ -173,18 +173,35 @@ The following additional variables can be used to control the behaviour
     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.
+
 - **`PARSERS`:**
   A white·space‐separated list of parsers to use (default:
     `$(THISDIR)/parsers/*.xslt`).
 
+- **`EXTRAPARSERS`:**
+  The value of this variable is appended to `PARSERS` by default, to
+    enable additional parsers without overriding the existing ones.
+
 - **`TRANSFORMS`:**
   A white·space‐separated list of transforms to use (default:
     `$(THISDIR)/transforms/*.xslt`).
 
+- **`EXTRATRANSFORMS`:**
+  The value of this variable is appended to `TRANSFORMS` by default, to
+    enable additional transforms without overriding the existing ones.
+
 - **`XMLTYPES`:**
   A white·space‐separated list of media types to consider X·M·L
     (default: `application/xml text/xml`).