src/Doc/System/Sessions.thy

     \<^theory_text>\<open>section\<close> etc. The default is \<^verbatim>\<open>isamarkup\<close>, e.g. \<^theory_text>\<open>section\<close> becomes
     \<^verbatim>\<open>\isamarkupsection\<close>.
 
     \<^item> @{system_option_def "threads"} determines the number of worker threads
     for parallel checking of theories and proofs. The default \<open>0\<close> means that a
-    sensible maximum value is determined by the underlying hardware. For
-    machines with many cores or with hyperthreading, this sometimes requires
-    manual adjustment (on the command-line or within personal settings or
-    preferences, not within a session \<^verbatim>\<open>ROOT\<close>).
+    sensible value is guessed from the underlying hardware. This sometimes
+    requires manual adjustment (on the command-line or within personal
+    settings or preferences, not within a session \<^verbatim>\<open>ROOT\<close>).
 
     \<^item> @{system_option_def "condition"} specifies a comma-separated list of
     process environment variables (or Isabelle settings) that are required for
     the subsequent theories to be processed. Conditions are considered
     ``true'' if the corresponding environment value is defined and non-empty.