  We consider diagrams with up to four t-channel gluons in order to specify
gluonic twist-four contributions to deep inelastic structure functions. This
enables us to extend the method developed by R.K.Ellis, W.Furmanski, and
R.Petronzio (EFP) to the gluonic case. The method is based on low-order Feynman
diagrams in combination with a dimensional analysis. It results in explicitly
gauge invariant expressions for the factorization of twist-four gluon-operator
matrix elements and the corresponding coefficient functions.
