Index: x/installing/tuning-fontconfig.xml
===================================================================
--- x/installing/tuning-fontconfig.xml	(revision fe9d1b1db974f422f41fe45ee096f6895473cad7)
+++ x/installing/tuning-fontconfig.xml	(revision 1f9b99fd99601a62163904478bdaeb3d5015fcc1)
@@ -244,17 +244,74 @@
       following rules come into play: First,
       <filename>30-metric-aliases.conf</filename> is used to map aliases for
-      some fonts with the same metrics (same size, etc). After that, an
-      unknown font will be searched for in <filename>45-latin.conf</filename>:
+      some fonts with the same metrics (same size, etc). Note that there are
+      both weak and strong aliases so that aliases for one form such as
+      Helvetica or Times New Roman can be stisfied by the other style, i.e.
+      anything which is an alias of Arial or Times in those examples.
+      After that, an unknown font will be searched for in
+      <filename>45-latin.conf</filename>:
       'latin' covers cyrillic and greek, and now also maps system-ui fonts which
       are used for User Interface messages in non-latin alphabets. If the font
       is found it will be mapped as serif, sans-serif, monospace, fantasy,
       cursive, or system-ui.  Otherwise, 49-sansserif.conf will assume it is
-      Sans. Then <filename>60-latin.conf</filename>
-      provides ordered lists of the fallbacks - <xref linkend="dejavu-fonts"/>
+      Sans.
+    </para>
+    <para>
+      Then <filename>60-latin.conf</filename>
+      provides ordered lists of the fallbacks - <xref linkend="noto-fonts"/>
       will be used if you installed them. Cyrillic and Greek appear to be
       treated in the same way. There are similar files with a 65- prefix for
       Persian and other non-latin writing systems. All of these files prefer
       commercial fonts if they are present, although modern libre fonts are
-      often at least equal.
+      often at least equal. Finally, if a codepoint is still not found it can
+      be taken from any available system font. The following details only
+      mention freely available fonts.
+    </para>
+
+    <para>
+      Before fontconfig-2.14, the first preferred font family was Bitstream
+      Vera. In practice that was rarely used because it covered so little. After
+      that, DejaVu was the next preferred family, so people were recommended to
+      install that. That has now changed, Bitstream Vera has been replaced by the
+      relevant Noto fonts (Serif, Sans, Sans Mono), so these will be preferred if
+      they have been installed, followed by DejaVu.
+    </para>
+
+    <para>
+      For serif, Times New Roman could have been aliased from Liberation Serif or
+      Tinos, and Times from TeX Gyre Termes, so although the named fonts are not
+      free, the metric-compatilbe fonts can be used. Ignoring other non-free fonts,
+      the remaining order for serif is: Times New Roman, Luxi Serif, Nimbus Roman
+      No9 L, Times. In practice, that means those fonts at the end of the list
+      are unlikely to be used unless a web page asks for them.
+    </para>
+
+    <para>
+      For sans-serif, the remaining order is anything mapped to Arial, Luxi Sans,
+      Nimbus Sans L, anything mapped to Helvetica.
+    </para>
+
+    <para>
+      The remaining alternatives for monospace are Inconsolata, anything mapped
+      to Courier New, Luxi Mono, Nimbus Mono, anything mapped to Courier.
+    </para>
+
+    <para>
+      For 'fantasy' there are no free fonts, so fontconfig will fall back to
+      sans-serif.
+    </para>
+
+    <para>
+      For 'cursive', the only free font is TeX Gyre Chorus as an alias for
+      ITC Zapf chancery, otherwise fontconfig will again fall back to sans-serif.
+    </para>
+
+    <para>
+      The system-ui category is unusual. It is for interface messages, so some
+      scripts need special versions to fit in the available space. For latin,
+      greek and cyrillic a normal sans font should fit without problems. However,
+      the first preferred font is Cantarell, followed by Noto Sans UI. Cantarell
+      started as a latin sans-serif font, that has been forked in gnome under
+      the same name but they only provide the source. The Noto Sans UI fonts are
+      for other languages.
     </para>
 
