docs(ref): document most of mp_units.core

docs/api_reference/src/macros_extensions.tex

@@ -1,5 +1,13 @@
 \newcommand{\IsoCpp}{N4971}
 
+\newcommand{\txtrm}[1]{\textnormal{\textrm{#1}}}
+
+\newcommand{\stdconcept}[1]{#1}
+
+\newcommand{\indexlibraryglobalexpos}[1]{\indexlibrary{#1@\exposid{#1}}}
+\newcommand{\indexlibraryctorexpos}[1]{\indexlibrarymisc{#1@\exposid{#1}}{constructor}}
+\newcommand{\indexlibraryexposmemberexpos}[2]{\indexlibraryboth{#1@\exposid{#1}}{#2@\exposid{#2}}}
+
 %% Inline non-parenthesized C++ reference
 \newcommand{\refcpp}[1]{\href{https://wg21.link/#1}{\IsoCpp{}, [#1]}}
 \newcommand{\irefcpp}[1]{\nolinebreak[3] (\refcpp{#1})}
@@ -8,4 +16,15 @@
 
 %% Inline IEV reference
 \newcommand{\refiev}[1]{\href{https://www.electropedia.org/iev/iev.nsf/display?openform&ievref=#1}{IEC 60050, #1}}
-\newcommand{\irefiev}[1]{\nolinebreak[3] (\refiev{#1})}
+\ExplSyntaxOn
+\NewDocumentCommand \irefiev { m } {
+  \clist_set:Nx \l_tmpa_clist { #1 }
+  \nolinebreak[3] ~ (
+  \clist_map_inline:Nn \l_tmpa_clist {
+    \clist_put_right:Nn \g_tmpa_clist { \refiev{##1} }
+  }
+  \clist_use:Nn \g_tmpa_clist { ,~ }
+  )
+  \clist_clear:N \g_tmpa_clist
+}
+\ExplSyntaxOff