diff --git a/eos/messages/eos_messages.proto b/eos/messages/eos_messages.proto
index 251a7227ace1d9df114a0429f50785113b94535d..6c2d6280e66c88a798a149a7ed3b693d0020f62e 100644
--- a/eos/messages/eos_messages.proto
+++ b/eos/messages/eos_messages.proto
@@ -1,101 +1,114 @@
-syntax = "proto3";
+syntax  = "proto3";
 package eos.wfe;
 
-message Id {
-  fixed64 uid = 1;      //< user identity number
-  string username = 2;  //< user name 
-  fixed64 gid = 3;      //< group identity number
-  string groupname = 4; //< group name
+message Checksum {
+  string value               = 1;       //< checksum value
+  string name                = 2;       //< checksum name
 }
 
-message Checksum {
-  string value = 1;      //< checksum value
-  string name = 2;       //< checksum name
+
+
+//
+// Messages sent from EOS to CTA
+//
+
+message Id {
+  uint64 uid                 = 1;       //< user identity number
+  string username            = 2;       //< user name 
+  uint64 gid                 = 3;       //< group identity number
+  string groupname           = 4;       //< group name
 }
 
 message Clock {
-  fixed64 sec = 1;       //< seconds of a clock
-  fixed64 nsec = 2;      //< nanoseconds of a clock
+  uint64 sec                 = 1;       //< seconds of a clock
+  uint64 nsec                = 2;       //< nanoseconds of a clock
 }
 
-message Md {
-  fixed64 fid = 1;       //< file/container id
-  fixed64 pid = 2;       //< parent id
-  Clock ctime = 3;       //< change time
-  Clock mtime = 4;       //< modification time
-  Clock btime = 5;       //< birth time
-  Clock ttime = 6;       //< tree modification time
-  Id owner = 7;          //< ownership
-  fixed64 size = 8;      //< size 
-  Checksum cks = 9;      //< checksum information
-  sfixed32 mode = 10;    //< mode
-  string lpath = 11;     //< logical path
-  map<string, string> xattr = 12; //< xattribute map
+message Metadata {
+  uint64 fid                 = 1;       //< file/container id
+  uint64 pid                 = 2;       //< parent id
+  Clock ctime                = 3;       //< change time
+  Clock mtime                = 4;       //< modification time
+  Clock btime                = 5;       //< birth time
+  Clock ttime                = 6;       //< tree modification time
+  Id owner                   = 7;       //< ownership
+  uint64 size                = 8;       //< size 
+  Checksum cks               = 9;       //< checksum information
+  sint32 mode                = 10;      //< mode
+  string lpath               = 11;      //< logical path
+  map<string, string> xattr  = 12;      //< xattribute map
 };
 
 message Security {
-  string host = 1;       //< client host 
-  string app = 2;        //< app string
-  string name = 3;       //< sec name
-  string prot = 4;       //< security protocol
-  string grps = 5;       //< security grps
+  string host                = 1;       //< client host 
+  string app                 = 2;       //< app string
+  string name                = 3;       //< sec name
+  string prot                = 4;       //< security protocol
+  string grps                = 5;       //< security grps
 }
 
 message Client {
-  Id user = 1;           //< acting client
-  Security sec = 2;      //< client security information
+  Id user                    = 1;       //< acting client
+  Security sec               = 2;       //< client security information
 }
 
 message Service {
-  string name = 1;       //< name of the service
-  string url = 2;        //< access url of the service
+  string name                = 1;       //< name of the service
+  string url                 = 2;       //< access url of the service
 }
 
 message Workflow {
   enum EventType {
-    NONE = 0;
-    OPENR = 1;
-    OPENW = 2;
-    CLOSER = 3;
-    CLOSEW = 4;
-    DELETE = 5;
-    PREPARE = 6;}
-  EventType event = 1;   //< event
-  string queue = 2;      //< queue
-  string wfname = 3;     //< workflow
-  string vpath = 4;      //< vpath
-  Service instance = 5;  //< instance information
-  fixed64 timestamp = 6; //< event timestamp
+    NONE    = 0;
+    OPENR   = 1;
+    OPENW   = 2;
+    CLOSER  = 3;
+    CLOSEW  = 4;
+    DELETE  = 5;
+    PREPARE = 6;
+  }
+  EventType event            = 1;       //< event
+  string queue               = 2;       //< queue
+  string wfname              = 3;       //< workflow
+  string vpath               = 4;       //< vpath
+  Service instance           = 5;       //< instance information
+  uint64 timestamp           = 6;       //< event timestamp
 }
 
 message Notification {
-  Workflow wf = 1;      //< workflow
-  string turl = 2;      //< transport URL
-  Client cli = 3;       //< client information
-  Md file = 4;          //< file meta data
-  Md directory = 5;     //< directory meta data
+  Workflow wf                = 1;       //< workflow
+  string turl                = 2;       //< transport URL
+  Client cli                 = 3;       //< client information
+  Metadata file              = 4;       //< file meta data
+  Metadata directory         = 5;       //< directory meta data
 }
 
+
+
+//
+// Messages sent from CTA to EOS
+//
+
 message Xattr {
-  enum Operation { NONE = 0; GET = 1; ADD = 2; SET = 3; DELETE = 4;}
-  fixed64 fid = 1;               //< file id
-  map<string, string> xattrs = 2; //< xattribute map
-  Operation op = 3;              //< operation to execute for this xattr map
+  enum Operation { NONE = 0; GET = 1; ADD = 2; SET = 3; DELETE = 4; }
+  uint64 fid                 = 1;       //< file id
+  map<string, string> xattr  = 2;       //< xattribute map
+  Operation op               = 3;       //< operation to execute for this xattr map
 }
 
 message Tapereplica {
-   enum Status { NONE = 0; OFFTAPE = 1; ONTAPE = 2; ONTAPESAVE = 3;}
-   fixed64 fid = 1;   //< file  id
-   Status status = 2; //< state state for file ID
-   fixed64 size = 3;  //< File size as recorded on tape for cross check
-   Checksum cks = 4;   //< File checksum as computer while writing to tape
+   enum Status { NONE = 0; OFFTAPE = 1; ONTAPE = 2; ONTAPESAVE = 3; }
+   uint64 fid                = 1;       //< file  id
+   Status status             = 2;       //< state state for file ID
+   uint64 size               = 3;       //< File size as recorded on tape for cross check
+   Checksum cks              = 4;       //< File checksum as computer while writing to tape
 }
 
 message Error {
-  enum Audience { NONE = 0; EOSLOG = 1; ENDUSER = 2;}
-  Audience audience = 1; //< The intended audience of the error message
-  fixed64 code = 2;      //< Zero means success, non-zero means error
-  string message = 3;    //< An empty if success, else an error message
+  enum Audience { NONE = 0; EOSLOG = 1; ENDUSER = 2; }
+  Audience audience          = 1;       //< The intended audience of the error message
+  uint64 code                = 2;       //< Zero means success, non-zero means error
+  string message             = 3;       //< An empty if success, else an error message
 }
 
 // The following message is used to wrap all messages sent between EOS and its
@@ -118,10 +131,10 @@ message Error {
 // contents. The type field of this wrapper message provides the required
 // metadata.
 message Wrapper {
-  enum Type {NONE = 0; ERROR = 1; NOTIFICATION = 2; XATTR = 3; TAPEREPLICA = 4;}
-  Type type = 1;
-  Error error = 2;
-  Notification notification = 3;
-  Xattr xattr = 4;
-  Tapereplica tapereplica = 5;
+  enum Type {NONE = 0; ERROR = 1; NOTIFICATION = 2; XATTR = 3; TAPEREPLICA = 4; }
+  Type type  = 1;
+  Error error  = 2;
+  Notification notification  = 3;
+  Xattr xattr  = 4;
+  Tapereplica tapereplica  = 5;
 }