When analyzing dichotomous data, ITEMAN
scores all unreached and omitted items as incorrect. Those
results are reported in the "other" alternative
statistics in the output file.
There are three options for handling such missing data in multipoint
items:
Itemwise deletion (only the missing responses are deleted
from the analysis);
Scalewise deletion (the examinees with missing responses
are deleted from only those scales that contain the
missing responses); and
Casewise deletion (examinees with missing responses are
deleted from all scales).
The three options are described in chapter 3 of the manual.
Source: Assessment Systems Corporation technical support