They are all different taxes withheld. Some are "income tax" withholding: FIT = Fed Income Tax, SIT = State Income Tax. These items go on your income tax return as payments against your income tax liability
FICA would be Social Security and Medicare which are not deductions nor credits on your income tax return.
TDI probably is some sort of state-level disability insurance payment, e.g. worker's comp. In California the State Disability Insurance (SDI) could be used as a Schedule A deduction. Might be the same in your state.
Not sure about FICM. Probably your employer has distinguished between Social Security, using FICA and Medicare using FICM.
You really should ask your employer's payroll department to be absolutely certain.
Tom Young
