diff --git a/index/alire-index-gnatcoll.ads b/index/alire-index-gnatcoll.ads
new file mode 100644
index 00000000..e9b3655d
--- /dev/null
+++ b/index/alire-index-gnatcoll.ads
@@ -0,0 +1,66 @@
+package Alire.Index.GNATCOLL is
+
+   function Project is new Catalogued_Project
+     ("GNAT Components Collection - Core packages");
+
+   Repo_AdaCore : constant URL := "https://github.com/AdaCore/gnatcoll-core.git";
+   --  Upstream
+
+   Repo_Alire   : constant URL := "https://github.com/alire-project/gnatcoll-core.git";
+   --  For slim picks
+
+   Base         : constant Release :=
+                    Project.Unreleased
+                      (Properties         =>
+                                          Author     ("AdaCore") and
+                         Maintainer ("alejandro@mosteo.com") and
+                         License    (GPL_3_0) and
+
+                         Project_File ("gnatcoll.gpr") and
+                         GPR_Scenario ("GNATCOLL_ATOMICS",
+                           "intrinsic" or "mutex") and
+                         GPR_Scenario ("GNATCOLL_OS",
+                           "windows" or "unix" or "osx") and
+                         GPR_Scenario ("BUILD",
+                           "DEBUG" or "PROD") and
+                         GPR_Scenario ("LIBRARY_TYPE",
+                           "relocatable" or "static" or "static-pic"),
+
+                       Private_Properties =>
+                         GPR_External ("BUILD", "PROD") and
+                         GPR_External ("LIBRARY_TYPE", "static-pic") and
+                         On_Condition
+                           (Operating_System = GNU_Linux,
+                            GPR_External ("GNATCOLL_OS", "unix")) and
+                         On_Condition
+                           (Operating_System = Windows,
+                            GPR_External ("GNATCOLL_OS", "windows")) and
+                         On_Condition
+                           (Operating_System = OSX,
+                            GPR_External ("GNATCOLL_OS", "osx")));
+
+   package Slim is
+
+      function Project is new Catalogued_Project
+        ("GNAT Components Collection - Slim version (no dependencies)");
+
+      package V_20180425 is new Released
+        (Base
+         .Replacing (Git (Repo_Alire,
+                          "81bc37d7548fe40024eb0f647df65ec42f65443b")));
+
+   end Slim;
+
+   package Strings is
+
+      function Project is new Catalogued_Project
+        ("GNAT Components Collection - Strings-only");
+
+      package V_20180425 is new Released
+        (Base
+         .Replacing (Git (Repo_Alire,
+                          "7823e31add7133b9fbc6e037d9986a823e840dc0")));
+
+   end Strings;
+
+end Alire.Index.GNATCOLL;
diff --git a/index/alire-index-xstrings.ads b/index/alire-index-xstrings.ads
new file mode 100644
index 00000000..1f7b826f
--- /dev/null
+++ b/index/alire-index-xstrings.ads
@@ -0,0 +1,24 @@
+with Alire.Index.GNATCOLL;
+
+package Alire.Index.XStrings is
+
+   function Project is new Catalogued_Project
+     ("Renaming of gnatcoll.strings without further dependencies");
+
+   Repo : constant URL := "https://github.com/alire-project/xstrings";
+
+   Base : constant Release :=
+            Project.Unreleased
+              (Dependencies =>
+                 GNATCOLL.Strings.V_20180425.Within_Major or
+                 GNATCOLL.Slim.V_20180425.Within_Major,
+
+               Properties =>
+                 Author     ("alejandro@mosteo.com") and
+                 License    (GPL_3_0));
+
+   package V_1_0_0 is new Released
+     (Base
+      .Replacing (Git (Repo, "40d3871dd644473aabac104666b4c83285b65ba6")));
+
+end Alire.Index.XStrings;
diff --git a/src/alire-index.adb b/src/alire-index.adb
index 24358bf3..6f2d6387 100644
--- a/src/alire-index.adb
+++ b/src/alire-index.adb
@@ -267,6 +267,12 @@ package body Alire.Index is
          return The_Release;
       end Release;
 
+      function Version return Semantic_Versioning.Version is
+        (The_Release.Version);
+
+      function Version return Semantic_Versioning.Version_Set is
+        (Exactly (The_Release.Version));
+
       function This_Version return Conditional.Dependencies is
          (The_Release.This_Version);
 
diff --git a/src/alire-index.ads b/src/alire-index.ads
index 4d11f03d..c10f7ed8 100644
--- a/src/alire-index.ads
+++ b/src/alire-index.ads
@@ -129,6 +129,9 @@ package Alire.Index is
       
       function Release return Index.Release;
       
+      function Version return Semantic_Versioning.Version;
+      function Version return Semantic_Versioning.Version_Set;
+      
       function This_Version return Conditional.Dependencies;
       function Within_Major return Conditional.Dependencies;
       function Within_Minor return Conditional.Dependencies;
@@ -225,7 +228,7 @@ package Alire.Index is
    --  Chained conditional dependencies (use first available)   
    
    function "or" (L, R : Release_Dependencies) return Release_Dependencies is (When_Available (L, R));
-   --  In the sense of "or else": the first one that is resolvable will be taken
+   --  In the sense of "or else": the first one that is available will be taken
    
    function "and" (L, R : Release_Dependencies) return Release_Dependencies 
                    renames Conditional.For_Dependencies."and";
diff --git a/src/alire-platforms.ads b/src/alire-platforms.ads
index c6968a51..b755dc0d 100644
--- a/src/alire-platforms.ads
+++ b/src/alire-platforms.ads
@@ -14,6 +14,7 @@ package Alire.Platforms with Preelaborate is
    --    isolate their versions
 
    type Operating_Systems is (GNU_Linux,
+                              OSX,
                               Windows,
                               OS_Unknown);