Add EXTRA* variables

[Shushe] / README.markdown

diff --git a/README.markdown b/README.markdown
index 3801b7eedeb3ca36e6783cc7f10d4020598502b1..654904ae9eda3ab787fbdc83dc7b001778f5ffda 100644 (file)
--- a/README.markdown
+++ b/README.markdown
@@ -1,6 +1,6 @@
 # ⛩️📰 书社
 
-<b>An X·S·L·T‐based static site generator.</b>
+<b>A make·file for X·M·L.</b>
 
 <dfn>⛩️📰 书社</dfn> aims to make it easy to generate websites with
   X·S·L·T and G·N·U Make.
@@ -18,6 +18,15 @@ It makes things easier by :⁠—
 
 It aims to do this with zero dependencies beyond the programs already
   installed on your computer.
+(On Linux machines, you may need to install `libxml2-utils` to get the
+  commandline programs from `libxml2`.)
+
+**Note:**
+⛩️📰 书社 requires functionality present in G·N·U Make 3.81 (or later)
+  and will not work in previous versions, or other implementations of
+  Make.
+Compatibility with later versions of G·N·U Make is assumed, but not
+  tested.
 
 ## Nomenclature
 
@@ -162,20 +171,37 @@ The following additional variables can be used to control the behaviour
   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, or pipe.
+    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`).
@@ -211,8 +237,8 @@ Source files whose media type does not have an associated X·S·L·T
 **☡ For compatibility with this program, source file·names must not
   contain Ascii white·space, colons (`:`), semis (`;`), pipes (`|`),
   bucks (`$`), percents (`%`), hashes (`#`), asterisks (`*`), brackets
-  (`[` or `]`), erotemes (`?`), or control characters, and must not
-  begin with a hyphen‐minus (`-`).**
+  (`[` or `]`), erotemes (`?`), backslashes (`\`), or control
+  characters, and must not begin with a hyphen‐minus (`-`).**
 The former characters have the potential to conflict with make syntax,
   and a leading hyphen‐minus is confusable for a command‐line argument.
 
@@ -462,4 +488,4 @@ Source files are licensed under the terms of the <cite>Mozilla Public
   License, version 2.0</cite>.
 For more information, see [LICENSE](./LICENSE).
 
-[draft-phillips-record-jar-01]: <https://datatracker.ietf.org/doc/html/draft-phillips-record-jar-01>
\ No newline at end of file
+[draft-phillips-record-jar-01]: <https://datatracker.ietf.org/doc/html/draft-phillips-record-jar-01>