packed decimal allocated length

hi

i saw multiple sap help docs but could not find out how the length of a packed decimal variable is allocated?

i mean if I declare

Data : abc type p length 16  decimals 2

will it allow 16 digits followed by a  decimal ( dot ) followed by 2 chars

xyz type p length 3 decimals 2

will it allow total 3 digits including decimal(dot ) and 2 decimal digits

please give a specific answer and not links as I have even debugged and seen that different lengths are allocated at diff times

thanks