  In covariant gauges, the gluonic mass gap in Yang-Mills theory manifests
itself in the basic observation that the massless pole in the perturbative
gluon propagator disappears in nonperturbative calculations, but the origin of
this behavior is not yet fully understood. We summarize a recent study of the
respective dynamics with Dyson-Schwinger equations in Landau-gauge Yang-Mills
theory. We identify the parameter that distinguishes the massive Yang-Mills
regime from the massless decoupling solutions, whose endpoint is the scaling
solution. Similar to the PT-BFM scheme, we find evidence that mass generation
in the transverse sector is triggered by longitudinal massless poles.
