For these two states, there is an additional M/S "Married/Single" type which is "B."
In these two states, a distinction is made between:
M - Married spouse does not work
B - Married, both spouses work
Pressing F1 while editing an employee in PR option A when in the M/S field will show this additional option if your employee is tied to a division that has a state code of MS or MO and, if linked to MS or MO, you will have the ability to enter a "B" as an additional type.
Employers in MO and MS should review the M/S type of all employees and change any "M's" to "B's" where pertinent.
Note: this is not specifically a 2003 issue. In MO, however, the ability to enter a "B" was not there in PR option A even though there was internal programming logic handling a "B" situation in PR option B. The 2003 update contains this change.