All,

Some textbooks use c with a subscript for propagation velocity. When
we use c for propagation velocity we can talk about a "particle"
accelerated to a velocity v such that

c_h2o v c_free_space

Closer to home, we can imagine a cosmic ray passing the shack with a
velocity such that

c_RG58 v c_ladder_line

I suggest anyone wishing to clarify his or her posts apply subscripts
to c to indicate how c is being used.

Thank you,

Steven, KD7YTE