IEBCOPY user TTR limits

Three user TTRN fields in the directory.
Only one of these fields may have n>0.
The maximum length of the note list record identified by the user TTRN with n>0 is 1291 bytes, including any block and record descriptor word.
No TTRN fields in a note list record may have n>0.
No user TTRN field in a note list record or in the partitioned data set directory may have the leftmost bit on (that is, the most significant bit of the first "T" in TTRN).

Figure 1. Note List Record Layout