-ALIASES += true="<b><tt>true</tt></b>"
-ALIASES += false="<b><tt>false</tt></b>"
-ALIASES += NULL="<b><tt>NULL</tt></b>"
+ALIASES += true="<span class='literal'>true</span>"
+ALIASES += false="<span class='literal'>false</span>"
+ALIASES += NULL="<span class='literal'>NULL</span>"
+
+# NOTE: these are important as you can't write in the docs
+# just #ifdef since the # character is used by Doxygen
+# for explicit linking; use the following aliases instead!
+# However to avoid overwriting e.g. \if Doxygen command the _
+# character is postfixed
+ALIASES += ifdef_="<span class='literal'>\#ifdef</span>"
+ALIASES += ifndef_="<span class='literal'>\#ifndef</span>"
+ALIASES += if_="<span class='literal'>\#if</span>"
+ALIASES += endif_="<span class='literal'>\#endif</span>"