added common rules: (common-file "%.o" ("%.c" "%.h") ...) etc.

SYNTAX

@@ -8,6 +8,11 @@ MAKEFILE:
 		      | <md5-clause> 
 		      | <always-clause> 
 		      | <once-clause>
+		      | <common-file-clause> 
+		      | <common-all-clause>
+		      | <common-md5-clause> 
+		      | <common-always-clause> 
+		      | <common-once-clause>
 
 <file-clause> ::= '(' + <fille-clause-identifier>
 		      + <target-spec> 
@@ -54,6 +59,49 @@ MAKEFILE:
 <once-clause-identifier> ::= "once" 
                              | "file-once"
 
+<common-file-clause> ::= '(' + <common-fille-clause-identifier>
+		      	     + <target-spec> 
+	              	     + <prereq-spec> 
+		      	     + <action>+ + ')'
+
+<common-all-clause> ::= '(' + <common-all-clause-identifier>
+		      	    + <target-spec> 
+	              	    + <prereq-spec> 
+		      	    + <action>+ + ')'
+
+<common-md5-clause> ::= '(' + <common-md5-clause-identifier>
+                     	    + <target-spec> 
+	             	    + <prereq-spec> 
+		     	    + <action-spec> + ')'
+
+<common-always-clause> ::= '(' + <common-always-clause-identifier>
+		               + <target-spec> 
+	                       + <prereq-spec> 
+		               + <action-spec> + ')'
+
+<common-once-clause> ::= '(' + <common-once-clause-identifier>
+		      	     + <target-spec> 
+	              	     + <prereq-spec> 
+		      	     + <action-spec> + ')'
+
+<common-file-clause-identifier> ::= "common-file" 
+                                    | "common-makefile-rule" 
+                                    | "common-is-out-of-date?"
+
+<common-all-clause-identifier> ::= "common-all" 
+                             	   | "common-file-all" 
+                             	   | "common-all-out-of-date?"
+
+<common-md5-clause-identifier> ::= "common-md5" 
+                                   | "common-file-md5" 
+                                   | "common-fp-changed?"
+
+<common-always-clause-identifier> ::= "common-always" 
+                                      | "common-file-always" 
+
+<common-once-clause-identifier> ::= "common-once" 
+                                    | "common-file-once"
+
 <target-spec> ::= <target> | <target-list>
 <target> ::= <filename>
 <target-list> ::= '(' + <filename>+ + ')'