  We construct operators that describe power corrections in mixed
collinear-ultrasoft processes in QCD. We treat the ultrasoft-collinear
Lagrangian to O(lambda^2), and heavy-to-light currents involving collinear
quarks to O(\lambda) including new three body currents. A complete gauge
invariant basis is derived which has a full reduction in Dirac structures and
is valid for matching at any order in alpha_s. The full set of
reparameterization invariance (RPI) constraints are included, and are found to
restrict the number of parameters appearing in Wilson coefficients and rule out
some classes of operators. The QCD ultrasoft-collinear Lagrangian has two
O(lambda^2) operators in its gauge invariant form. For the O(lambda)
heavy-to-light currents there are (4,4,14,14,21) subleading (scalar,
pseudo-scalar, vector, axial-vector, tensor) currents, where (1,1,4,4,7) have
coefficients that are not determined by RPI. In a frame where v_perp=0 and n.v
=1 the total number of currents reduces to (2,2,8,8,13), but the number of
undetermined coefficients is the same. The role of these operators and
universality of jet functions in the factorization theorem for heavy-to-light
form factors is discussed.
