src/Pure/Admin/build_history.scala

     arch_64: Boolean = false,
     heap: Int = default_heap,
     max_heap: Option[Int] = None,
     more_settings: List[String] = Nil,
     verbose: Boolean = false,
+    build_tags: List[String] = Nil,
     build_args: List[String] = Nil): List[(Process_Result, Path)] =
   {
     /* sanity checks */
 
     if (File.eq(Path.explode("~~"), hg.root))

       val build_end = Date.now()
 
       val log_path =
         other_isabelle.isabelle_home_user +
           Build_Log.log_subdir(build_history_date) +
-          Build_Log.log_filename(
-            BUILD_HISTORY, build_history_date, build_host, ml_platform, "M" + threads)
+          Build_Log.log_filename(BUILD_HISTORY, build_history_date,
+            List(build_host, ml_platform, "M" + threads) ::: build_tags)
 
       val build_info =
         Build_Log.Log_File(log_path.base.implode, build_result.out_lines).parse_build_info()
 
 
       /* output log */
 
       val meta_info =
+        (if (build_tags.isEmpty) Nil
+         else List(Build_Log.Field.build_tags -> Word.implode(build_tags))) :::
         List(
           Build_Log.Field.build_group_id -> build_group_id,
           Build_Log.Field.build_id -> (build_host + ":" + build_start.time.ms),
           Build_Log.Field.build_engine -> BUILD_HISTORY,
           Build_Log.Field.build_host -> build_host,

       var more_settings: List[String] = Nil
       var fresh = false
       var arch_64 = false
       var nonfree = false
       var rev = default_rev
+      var build_tags = List.empty[String]
       var verbose = false
 
       val getopts = Getopts("""
 Usage: isabelle build_history [OPTIONS] REPOSITORY [ARGS ...]
 

     -e TEXT      additional text for generated etc/settings
     -f           fresh build of Isabelle/Scala components (recommended)
     -m ARCH      processor architecture (32=x86, 64=x86_64, default: x86)
     -n           include nonfree components
     -r REV       update to revision (default: """ + default_rev + """)
+    -t TAG       free-form build tag (multiple occurrences possible)
     -v           verbose
 
   Build Isabelle sessions from the history of another REPOSITORY clone,
   passing ARGS directly to its isabelle build tool.
 """,

             case "64" | "x86_64" => arch_64 = true
             case bad => error("Bad processor architecture: " + quote(bad))
           },
         "n" -> (_ => nonfree = true),
         "r:" -> (arg => rev = arg),
+        "t:" -> (arg => build_tags = build_tags ::: List(arg)),
         "v" -> (_ => verbose = true))
 
       val more_args = getopts(args)
       val (root, build_args) =
         more_args match {

         build_history(hg, progress = progress, rev = rev, isabelle_identifier = isabelle_identifier,
           components_base = components_base, fresh = fresh, nonfree = nonfree,
           multicore_base = multicore_base, threads_list = threads_list, arch_64 = arch_64,
           heap = heap.getOrElse(if (arch_64) default_heap * 2 else default_heap),
           max_heap = max_heap, more_settings = more_settings, verbose = verbose,
-          build_args = build_args)
+          build_tags = build_tags, build_args = build_args)
 
       for ((_, log_path) <- results)
         Output.writeln(log_path.implode, stdout = true)
 
       val rc = (0 /: results) { case (rc, (res, _)) => rc max res.rc }