Area for retaining the grade portion (1 digit) of the ICD-O-1 or field trial grade code entered before a conversion to ICD-O-2. See grouped data item Morph (73-91) ICD-O-1 [1970] in Appendix E. The item name includes years 1973-91. However, some states may have used the codes for cases before 1973.

Codes
For cases diagnosed before 1992, contains the ICD-O-1 or field trial 1-digit grade code as originally coded, if available.^{18, 19}