 
 : read-data ( loading-gif -- loading-gif )
     read1 {
-        { extension-identifier [ read-extension ] }
-        { graphic-control-extension [
+        { EXTENSION-IDENTIFIER [ read-extension ] }
+        { GRAPHICS-CONTROL-EXTENSION [
             read-graphic-control-extension
             over graphic-control-extensions>> push
         ] }
-        { image-descriptor [ read-table-based-image ] }
-        { trailer [ f >>loading? ] }
+        { IMAGE-DESCRIPTOR [ read-table-based-image ] }
+        { TRAILER [ f >>loading? ] }
         [ unhandled-data ]
     } case ;
 


: read-extension ( loading-gif -- loading-gif )
    read1 {
        { plain-text-extension [
            read-plain-text-extension over plain-text-extensions>> push
        ] }

        { graphic-control-extension [
            read-graphic-control-extension
            over graphic-control-extensions>> push
        ] }
        { comment-extension [
            read-comment-extension over comment-extensions>> push
        ] }
        { application-extension [
            read-application-extension over application-extensions>> push
        ] }
        { f [ gif-unexpected-eof ] }


: read-graphic-control-extension ( -- graphic-control-extension )
    \ graphics-control-extension new
        1 read le> GRAPHIC-CONTROL-EXTENSION-BLOCK-SIZE assert=
        1 read le> >>flags
        2 read le> >>delay-time
        1 read le> >>transparent-color-index
        1 read le> BLOCK-TERMINATOR assert= ;

: read-plain-text-extension ( -- plain-text-extension )
    \ plain-text-extension new
