Using HeapTuple.t_len to verify size of tuple

Hello,

Can the t_len field in HeapTuple structure be used to verify the length of
the tuple?

That is, if I calculate the length from the contents of the tuple using
data from pg_attribute for fixed length fields and the data from the header
for varlena fields, should it always match the value stored in t_len?

Thanks,
VIgnesh