language-snippets.ent Explain codepoints and add tags (#3932)

* language-snippets.ent Explain the meaning of nums and add tags

* language-snippets.ent Replace dec codepoint to mnemonics

Author: mmalferov

language-snippets.ent

@@ -3778,32 +3778,38 @@ local: {
  <itemizedlist xmlns="http://docbook.org/ns/docbook">
     <listitem>
      <simpara>
-      <literal>" "</literal> (<acronym>ASCII</acronym> 32 (0x20)), an ordinary space.
+      <literal>" "</literal>: <acronym>ASCII</acronym> <acronym>SP</acronym> character
+      <literal>0x20</literal>, an ordinary space.
      </simpara>
     </listitem>
     <listitem>
      <simpara>
-      <literal>"\t"</literal> (<acronym>ASCII</acronym> 9 (0x09)), a tab.
+      <literal>"\t"</literal>: <acronym>ASCII</acronym> <acronym>HT</acronym> character
+      <literal>0x09</literal>, a tab.
      </simpara>
     </listitem>
     <listitem>
      <simpara>
-      <literal>"\n"</literal> (<acronym>ASCII</acronym> 10 (0x0A)), a new line (line feed).
+      <literal>"\n"</literal>: <acronym>ASCII</acronym> <acronym>LF</acronym> character
+      <literal>0x0A</literal>, a new line (line feed).
      </simpara>
     </listitem>
     <listitem>
      <simpara>
-      <literal>"\r"</literal> (<acronym>ASCII</acronym> 13 (0x0D)), a carriage return.
+      <literal>"\r"</literal>: <acronym>ASCII</acronym> <acronym>CR</acronym> character
+      <literal>0x0D</literal>, a carriage return.
      </simpara>
     </listitem>
     <listitem>
      <simpara>
-      <literal>"\0"</literal> (<acronym>ASCII</acronym> 0 (0x00)), the NUL-byte.
+      <literal>"\0"</literal>: <acronym>ASCII</acronym> <acronym>NUL</acronym> character
+      <literal>0x00</literal>, the NUL-byte.
      </simpara>
     </listitem>
     <listitem>
      <simpara>
-      <literal>"\v"</literal> (<acronym>ASCII</acronym> 11 (0x0B)), a vertical tab.
+      <literal>"\v"</literal>: <acronym>ASCII</acronym> <acronym>VT</acronym>
+      character <literal>0x0B</literal>, a vertical tab.
      </simpara>
     </listitem>
    </itemizedlist>