It is well known that for the comparison and combination of geodetic n
etworks their heterogeneous datum definitions are well to be considere
d. Various algorithms have been developed for this purpose. As an alte
rnative concept to deal with hybrid datum problems, the operator paral
lel sum of matrices is introduced in this paper. To begin with, a defi
nition is given and some basic properties are explained. To demonstrat
e the usefulness of the operator, two practical applications are given
. The first deals with the estimation of parameters describing the def
ormation of two networks which are to be compared to each other. The s
econd one treats the estimation of parameters representing the heterog
eneous datum definitions of two networks which are to be merged into a
hybrid network. It will be shown that - regardless of the datum defin
itions of the preadjusted individual networks - the parallel sum of ma
trices can be used to simplify the algorithms applied for the estimati
on of those parameters.