National ID were given as two different numbers as Malaysia adopted a new format in 1991 which incorporated birth date information, state and gender into the formation of the number.

YYMMDD-SS-RRRG
YYMMDD - Format is Year-Month-Date
SS - State of Birth
RRR - Random numbers
G - Gender

Whilst the older one denote (B) for Biru (Blue), the colour the ID card to differentiate between citizen, permanent resident and other alien. Blue-coloured ID was for citizen.