10 files changed, 23 insertions, 85 deletions
diff --git a/doc/tutorial/third-party-software.org b/doc/tutorial/third-party-software.org
index e088bc4b..7bce1c48 100644
--- a/doc/tutorial/third-party-software.org
+++ b/doc/tutorial/third-party-software.org
@@ -55,7 +55,7 @@ $ mkdir -p fmt-layer/src
 #+END_SRC
 
 The directory ~include/fmt~ contains only header files. As we want all files in
-this directory to be included in the ~"header directory"~ target, we can safely
+this directory to be included in the ~"hdrs"~ target, we can safely
 use the explicit ~TREE~ reference[fn:1], which collects, in a single
 artifact (describing a directory) /all/ directory contents
 from ~"."~ of the workspace root. Note that the ~TARGETS~ file is only part of
@@ -74,15 +74,15 @@ references from the current module.
 #+SRCNAME: fmt-layer/include/fmt/TARGETS
 #+BEGIN_SRC js
 { "hdrs":
-  { "type": ["@", "rules", "CC", "header directory"]
-  , "hdrs": [["TREE", null, "."]]
+  { "type": ["@", "rules", "data", "staged"]
+  , "srcs": [["TREE", null, "."]]
   , "stage": ["fmt"]
   }
 }
 #+END_SRC
 
 The actual library target is defined in the directory ~src~. For the public
-headers, it refers to the previously created header directory via its
+headers, it refers to the previously created ~"hdrs"~ target via its
 fully-qualified target name (~["include/fmt", "hdrs"]~). Source files are the
 two local files ~format.cc~, and ~os.cc~. The final target description in
 ~src/TARGETS~ will look like this:
diff --git a/etc/import.prebuilt/TARGETS.gsl b/etc/import.prebuilt/TARGETS.gsl
index df06ea7e..b8b6798f 100644
--- a/etc/import.prebuilt/TARGETS.gsl
+++ b/etc/import.prebuilt/TARGETS.gsl
@@ -1,8 +1,8 @@
 { "gsl-lite":
   {"type": ["@", "rules", "CC", "library"], "hdrs": ["gsl-lite hdrs"]}
 , "gsl-lite hdrs":
-  { "type": ["@", "rules", "CC", "header directory"]
-  , "hdrs": ["gsl", "gsl-lite.h", "gsl-lite.hpp", "gsl-lite-vc6.hpp"]
-  , "stage": ["gsl-lite"]
+  { "type": "tree"
+  , "name": "gsl-lite"
+  , "deps": ["gsl", "gsl-lite.h", "gsl-lite.hpp", "gsl-lite-vc6.hpp"]
   }
 }
diff --git a/etc/import.prebuilt/TARGETS.json b/etc/import.prebuilt/TARGETS.json
index df94fa83..fcb2936b 100644
--- a/etc/import.prebuilt/TARGETS.json
+++ b/etc/import.prebuilt/TARGETS.json
@@ -1,7 +1,4 @@
 { "json": {"type": ["@", "rules", "CC", "library"], "hdrs": ["json headers"]}
 , "json headers":
-  { "type": ["@", "rules", "CC", "header directory"]
-  , "stage": ["nlohmann"]
-  , "hdrs": [["TREE", null, "."]]
-  }
+  {"type": "tree", "name": "nlohmann", "deps": [["TREE", null, "."]]}
 }
diff --git a/etc/import/TARGETS.gsl b/etc/import/TARGETS.gsl
index df06ea7e..b8b6798f 100644
--- a/etc/import/TARGETS.gsl
+++ b/etc/import/TARGETS.gsl
@@ -1,8 +1,8 @@
 { "gsl-lite":
   {"type": ["@", "rules", "CC", "library"], "hdrs": ["gsl-lite hdrs"]}
 , "gsl-lite hdrs":
-  { "type": ["@", "rules", "CC", "header directory"]
-  , "hdrs": ["gsl", "gsl-lite.h", "gsl-lite.hpp", "gsl-lite-vc6.hpp"]
-  , "stage": ["gsl-lite"]
+  { "type": "tree"
+  , "name": "gsl-lite"
+  , "deps": ["gsl", "gsl-lite.h", "gsl-lite.hpp", "gsl-lite-vc6.hpp"]
   }
 }
diff --git a/etc/import/TARGETS.json b/etc/import/TARGETS.json
index df94fa83..f1aea866 100644
--- a/etc/import/TARGETS.json
+++ b/etc/import/TARGETS.json
@@ -1,7 +1,7 @@
 { "json": {"type": ["@", "rules", "CC", "library"], "hdrs": ["json headers"]}
 , "json headers":
-  { "type": ["@", "rules", "CC", "header directory"]
+  { "type": ["@", "rules", "data", "staged"]
   , "stage": ["nlohmann"]
-  , "hdrs": [["TREE", null, "."]]
+  , "srcs": [["TREE", null, "."]]
   }
 }
diff --git a/etc/import/include/CLI/TARGETS.cli11 b/etc/import/include/CLI/TARGETS.cli11
index d9764847..b769de60 100644
--- a/etc/import/include/CLI/TARGETS.cli11
+++ b/etc/import/include/CLI/TARGETS.cli11
@@ -1,7 +1,7 @@
 { "cli11_headers":
-  { "type": ["@", "rules", "CC", "header directory"]
-  , "stage": ["CLI"]
-  , "hdrs":
+  { "type": "tree"
+  , "name": "CLI"
+  , "deps":
     [ "Option.hpp"
     , "Split.hpp"
     , "Formatter.hpp"
diff --git a/etc/import/include/fmt/TARGETS.fmt b/etc/import/include/fmt/TARGETS.fmt
index 72ea6d52..37f21a15 100644
--- a/etc/import/include/fmt/TARGETS.fmt
+++ b/etc/import/include/fmt/TARGETS.fmt
@@ -1,6 +1,6 @@
 { "hdrs":
-  { "type": ["@", "rules", "CC", "header directory"]
+  { "type": ["@", "rules", "data", "staged"]
   , "stage": ["fmt"]
-  , "hdrs": [["TREE", null, "."]]
+  , "srcs": [["TREE", null, "."]]
   }
 }
diff --git a/etc/import/include/git2/TARGETS.git2 b/etc/import/include/git2/TARGETS.git2
index 84eb50c3..a9dad131 100644
--- a/etc/import/include/git2/TARGETS.git2
+++ b/etc/import/include/git2/TARGETS.git2
@@ -150,9 +150,9 @@
   , "patch-part": ["a", "include", "git2", "sys", "repository.h"]
   }
 , "TREE":
-  { "type": ["@", "rules", "CC", "header directory"]
-  , "stage": ["git2"]
-  , "hdrs":
+  { "type": "tree"
+  , "name": "git2"
+  , "deps":
     [ "annotated_commit.h"
     , "apply.h"
     , "attr.h"
diff --git a/rules/CC/RULES b/rules/CC/RULES
index ab01a50f..9e599e19 100644
--- a/rules/CC/RULES
+++ b/rules/CC/RULES
@@ -109,65 +109,6 @@
       }
     }
   }
-, "header directory":
-  { "doc":
-    [ "A directory of header files."
-    , ""
-    , "Define a directory of  header files that belong together and are staged"
-    , "in such a way that no other target (used together with this target) will"
-    , "have to put files in this directory. The typical use case is a library"
-    , "libfoo that expects all headers to be included as #include \"foo/bar.h\"."
-    , "In this case, one would define a header direcotry for \"foo\"."
-    , ""
-    , "Technically, a tree is created from the given files and staged to the"
-    , "specified location. Since trees are opaque, the directory name becomes"
-    , "essentially owned by target. In this way, staging conflicts can be"
-    , "avoided by detecting them early and not only once a file with the same"
-    , "name is  added to the staging location. Also, as only a tree identifier"
-    , "has to be passed around, such a directory can be handled more"
-    , "efficiently by the tool."
-    ]
-  , "target_fields": ["hdrs"]
-  , "string_fields": ["stage"]
-  , "field_doc":
-    { "hdrs": ["The header files to be put into the header directory."]
-    , "stage":
-      [ "The location of the header directory."
-      , "Path segments are joined with \"/\"."
-      ]
-    }
-  , "artifacts_doc": ["The single tree artifact staged to the given location"]
-  , "runfiles_doc": ["Same as artifacts"]
-  , "imports": {"runfiles": ["./", "..", "field_runfiles"]}
-  , "expression":
-    { "type": "let*"
-    , "bindings":
-      [ [ "hdrs"
-        , { "type": "let*"
-          , "bindings": [["fieldname", "hdrs"]]
-          , "body": {"type": "CALL_EXPRESSION", "name": "runfiles"}
-          }
-        ]
-      , [ "stage"
-        , { "type": "join"
-          , "separator": "/"
-          , "$1": {"type": "FIELD", "name": "stage"}
-          }
-        ]
-      , [ "dir"
-        , { "type": "singleton_map"
-          , "key": {"type": "var", "name": "stage"}
-          , "value": {"type": "TREE", "$1": {"type": "var", "name": "hdrs"}}
-          }
-        ]
-      ]
-    , "body":
-      { "type": "RESULT"
-      , "artifacts": {"type": "var", "name": "dir"}
-      , "runfiles": {"type": "var", "name": "dir"}
-      }
-    }
-  }
 , "library":
   { "doc": ["A C++ libaray"]
   , "target_fields":
diff --git a/test/end-to-end/target-cache/test-data-artifacts-sync/greetlib/greet/include/TARGETS b/test/end-to-end/target-cache/test-data-artifacts-sync/greetlib/greet/include/TARGETS
index 6093f6f4..1574e83c 100644
--- a/test/end-to-end/target-cache/test-data-artifacts-sync/greetlib/greet/include/TARGETS
+++ b/test/end-to-end/target-cache/test-data-artifacts-sync/greetlib/greet/include/TARGETS
@@ -1,6 +1,6 @@
 { "hdrs":
-  { "type": ["@", "rules", "CC", "header directory"]
-  , "hdrs": [["TREE", null, "."]]
+  { "type": ["@", "rules", "data", "staged"]
+  , "srcs": [["TREE", null, "."]]
   , "stage": ["greet"]
   }
 }