Adding Mortality Data to NHIS

I have provided the Excel code in order to create a time lapsed since the beginning of the interview.

Completed SPSS Notes (DODMTH already in the syntax that I wrote to convert variables)

DODMTH was created in SPSS
RECODE MORTDODQ (1=2)(2=5)(3=8)(4=11) into DODMTH.
EXECUTE.

Excel Notes
=TEXT(CN2&"/"&CG2,"mmm-yyyy")
CG2=MORTDODY (CG2 cell varies according to worksheet)
CN2=DODMTH  (CN2 cell varies according to worksheet)
Variable=CO2=Mo_Yr* (depending on where this is being written)

=TEXT(R2&"/"&S2,"mmm-yyyy")
R2=INTERVMO
S2=INTERVWYR
Variable=CP2=Mo_Yr2*

Synthesized Variables
Months*
=(YEAR(CO2)-YEAR(CP2))*12+MONTH(CO2)-MONTH(CP2)
Created variables from the previous 2 equations
CO2=Mo_Yr
CP2=Mo_Yr2

*Bolded words are variable names.