The documentation for isql incorrectly describes the -K keytab_file parameter.
The description in the Utility Guide for the isql -K keytab_file parameter currently reads:
-K keytab_file
specifies the path to the keytab file used for authentication in DCE. keytab_file specifies a DCE keytab that contains the security key for the user name you specify in -U. Create keytab files using the DCE dcecp utility. See your DCE documentation. If you do not specify -K, the isql user must be logged in to DCE with the same user name specified in -U.
The correct description for the -K keytab_file parameter is:
(used only with Kerberos security) specifies a Kerberos keytab file that contains the security key for the user name specified with the -U option. To create a keytab, see your Kerberos documentation. If you do not specify the -K option, the isql user must be logged in to Kerberos with the same user name as specified with the -U option.