src/Doc/System/Environment.thy

   variables. Such advanced features should be added only with great care,
   though. In particular, external environment references should be kept at a
   minimum.
 
   \<^medskip>
-  A few variables are somewhat special, e.g. @{setting_def ISABELLE_TOOL} is
+  A few variables are somewhat special, e.g.\ @{setting_def ISABELLE_TOOL} is
   set automatically to the absolute path name of the @{executable isabelle}
   executables.
 
   \<^medskip>
   Note that the settings environment may be inspected with the @{tool getenv}

   \<^descr>[@{setting_def ISABELLE_TMP_PREFIX}\<open>\<^sup>*\<close>] is the prefix from which any
   running Isabelle ML process derives an individual directory for temporary
   files.
 
   \<^descr>[@{setting_def ISABELLE_TOOL_JAVA_OPTIONS}] is passed to the \<^verbatim>\<open>java\<close>
-  executable when running Isabelle tools (e.g. @{tool build}). This is
+  executable when running Isabelle tools (e.g.\ @{tool build}). This is
   occasionally helpful to provide more heap space, via additional options like
   \<^verbatim>\<open>-Xms1g -Xmx4g\<close>.
 \<close>