  Contributions to heavy flavour transition matrix elements in the variable
flavour number scheme are considered at 3-loop order. In particular a
calculation of the diagrams with two equal masses that contribute to the
massive operator matrix element $A_{gg,Q}^{(3)}$ is performed. In the Mellin
space result one finds finite nested binomial sums. In $x$-space these sums
correspond to iterated integrals over an alphabet containing also square-root
valued letters.
