A yes/no field entered as Y for Yes or N for No (some also allow None).
Many ODAG fields are yes/no questions entered as Y for Yes or N for No, such as 'Part B Drug Request?' and 'Was a timeframe extension taken?'. Some, such as 'Was the request denied for lack of medical necessity?', also allow None when the question does not apply.
Sources: ODAG protocol, Universe Table 1, Columns J, O and Y, PDF pp. 19-21; SNPCC protocol, Universe Table 1 SNPE Column ID N (PDF p. 12); Table 1IA Column IDs G-J, P-W (PDF pp. 15-18); CPE protocol, COA Columns K and L, p. 15.