SpinorV[p, m] denotes a v(p,m)-spinor that depends on the 4-dimensional momentum p.
Overview, Spinor, SpinorUBar, SpinorU, SpinorVBar, SpinorUBarD, SpinorUD, SpinorVD, SpinorVBarD.
SpinorV[p, m]v(p,m)
SpinorV[p, m] // FCI // StandardForm
(*Spinor[-Momentum[p], m, 1]*)SpinorV[p]v(p)
SpinorV[p] // FCI // StandardForm
(*Spinor[-Momentum[p], 0, 1]*)GS[p] . SpinorV[p]
DiracEquation[%]\left(\bar{\gamma }\cdot \overline{p}\right).v(p)
0