  The scale of a coupling constant for rapidity-only evolution of
transverse-momentum dependent (TMD) operators in the Sudakov kinematic region
is calculated using the Brodsky-Lepage-Mackenzie (BLM) optimal scale setting.
The effective argument of a coupling constant is halfway in the logarithmical
scale between the transverse momentum and energy of TMD distribution. The
resulting rapidity-only evolution equation is solved for quark and gluon TMDs.
