diff --git a/tests/grammar.md b/tests/grammar.md
index 616ae53..08ad129 100644
--- a/tests/grammar.md
+++ b/tests/grammar.md
@@ -1,3 +1,60 @@
+// Arbitrarily deep tree, possibly empty
+// file            : [@child set]
+// set             : '{' [@child set] '}' | set [' ' @sibling set]
+
+// Labeled leaves
+// file            : [@child set]
+// set             : @fill 'A' | '{' [@child set] '}' | set [' ' @sibling set]
+
+// Labels also on internal nodes    ('iset' is an implicitly separated set)
+// file                            : [@child set]
+// set                             : @fill 'A' [':' @child iset '\n'] | [@fill 'A' ':'] curly_set  | set [' ' @sibling set]
+// iset /* implicit separator */  : @fill 'A' [':' @child iset]      |  @fill 'A'[':'  curly_set] | @fill 'A' [' ' @sibling iset] | @fill 'A' [' ' @sibling curly_set]
+// curly_set                       : '{' [@child set] '}'
+
+// Labels also on internal nodes (v2) ('iset' is an implicitly separated set)
+// file                            : [@child set]
+// set                             : @fill 'A' [':' @child iset '\n'] | [@fill 'A' ':'] curly_set | set [' ' @sibling set]
+// iset /* implicit separator */   : @fill 'A' [iset_tail]
+// iset_tail                       : ':' @child iset | ' ' @sibling iset | ':'  curly_set | ' ' @sibling curly_set
+// curly_set                       : '{' [@child set] '}'
+
+// Tags
+// file          : [@child set]
+// set           : {[tag_list] untagged_set}
+// iset          : {[tag_list] untagged_iset}
+// tag_list      : '@' @tag tag ' ' [tag_list]
+// tag           : 'T'
+// untagged_set  : @fill 'A' [':' @child iset '\n'] | [@fill 'A' ':'] curly_set | set [' ' @sibling set]
+// untagged_iset : @fill 'A' [iset_tail]
+// iset_tail     : ':' @child iset | ' ' @sibling iset | ':'  curly_set | ' ' @sibling curly_set
+// curly_set     : '{' [@child set] '}'
+
+// Tag parameters
+file          : [@child set]
+set           : {[tag_list] untagged_set}
+iset          : {[tag_list] untagged_iset}
+tag_list      : '@' @tag tag ' ' [tag_list]
+tag           : @fill 'T'['(' [@child set] ')']
+untagged_set  : @fill 'A' [':' @child iset '\n'] | [@fill 'A' ':'] curly_set | set [' ' @sibling set]
+untagged_iset : @fill 'A' [iset_tail]
+iset_tail     : ':' @child iset | ' ' @sibling iset | ':'  curly_set | ' ' @sibling curly_set
+curly_set     : '{' [@child set] '}'
+
+
+// top-level and set separators
+// file            : [@child file_set_list]
+// file_set_list   : set [file_set_separator @sibling file_set_list]
+// file_set_separator   : ' ' | '\n'
+// set             : '{' [@child set] '}' | set [separator @sibling set]
+// separator       : ' ' | ','
+
+
+
+/////////////////////////////////////////// REFERENCE ///////////////////////////////////////////////////////////
+
+/*
+
 /* MetaDesk grammar with semantic annotations
  *
  * Each line represents a BNF-esque production:
@@ -13,17 +70,30 @@ file                 : [@child file_set_list]
 file_set_list        : { [tag_list] set [file_set_separator @sibling file_set_list] }
 file_set_separator   : ' ' | '\n'
 
-// TODO(mal): Unify file_set_separator and set_separator by allowing ',' and ';' everywhere
-set_list        : { [tag_list] set [set_separator @sibling file_set_list] }
-set_separator   : ' ' | '\n' | ',' | ';'
-                                        // TODO(mal): Accept other open/close tokens
+// TODO(mal): Unify file_set_separator and set_separator by allowing ',' and ';' everywhere ?
+set_list        : { [tag_list] set [set_separator @sibling set_list] }
+set_separator   : ' ' | '\n'        // TODO(mal):  | ',' | ';'
 tag_list        : '@' @tag tag ' ' [tag_list]
-tag             : identifier [@markup '(' [@child set_list] @markup ')']
-set             : @fill leaf | @fill identifier ':' @child @fill leaf | [@fill identifier ':'] set_open [@child set_list] set_close
-set_open        : '{' | '[' | '('
-set_close       : '}' | ']' | ')'
+
+/*
+    tag             : identifier [@markup '(' [@child set_list] @markup ')']
+    set             : @fill leaf | @fill identifier ':' @child @fill leaf | [@fill identifier ':'] '{' [@child set_list] '}' | [@fill identifier ':'] set_open [@child set_list] set_close
+    set             : @fill leaf | @fill identifier ':' @child space_separated_set_list | [@fill identifier ':'] set_open [@child set_list] set_close
+*/
+
+tag             : identifier 
+set             : @fill leaf [':' @child space_separated_set_list '\n'] | @fill leaf [':' '{' [@child set_list] '}'] | space_separated_set_list '\n' | '{' [@child set_list] '}' 
+
+space_separated_set_list : { [tag_list] set [' ' @sibling space_separated_set_list] }
+
+
+// set_open        : '[' | '('
+// set_close       : ']' | ')'
+set_open        : '['           // TODO(mal): Should also accept '('
+set_close       : ']'           // TODO(mal): Should also accept ')'
 leaf            : identifier | integer_literal | char_literal | string_literal  // TODO(mal): Also symbol_label
-identifier      : alpha [alphanumeric] | '_' [alphanumeric]
+identifier      : alpha [alphanumeric]
+name_identifier : alpha [alphanumeric]
 alphanumeric    : alpha [alphanumeric] | digit [alphanumeric] | '_' [alphanumeric]
 
 integer_literal : { ['-'] natural_literal }
@@ -64,13 +134,5 @@ escaped_char    : '\\' '\\' | '\\' '\'' | '\\' '\"'
 symbol_colon    : ':'
 
 */
-
-
-/*
-    // NOTE(mal): This is the simplest subset of the grammar that works
-    file            : [@child set_list]
-    set_list        : set ['\n' @sibling set_list]
-    set             : @fill element | '{' [@child set_list] '}'
-    element         : 'A'
 */