906 Level Number
TYPE=ID MIN=1 MAX=1
Loop repeat count as specified in the standard; the use of 9999999 in the electronic form is to be interpreted to mean >1
0 Application Data Segment
1 Application Control Segment (e.g., ST/SE)
2 Group Control Segment (e.g., GS/GE)
3 Interchange Control Segment (e.g., ISA/TA1/IEA)