fix #202

Author: podborski

data/item-references.csv

@@ -9,7 +9,6 @@ evir,EVC slice reference,item ref.,HEIF
 exbl,Scalable image item reference, item ref.,HEIF
 fdel,File delivery reference,item ref.,ISO
 font,Font item reference,item ref.,ISO
-grid,Image item grid reference,item ref.,HEIF
 iloc,Item data location,item ref.,ISO
 mask,Region mask reference,item ref.,HEIF
 mint,Data integrity reference,item ref.,HEIF