B00[pp, ma^2, mb^2]
is the Passarino-Veltman B_{00}-function, i.e., the coefficient function of the metric tensor. All arguments are scalars and have dimension mass squared.
[SPD[p], m^2, M^2] B00
\frac{\left(m^2-2 m M+M^2-p^2\right) \left(m^2+2 m M+M^2-p^2\right) \;\text{B}_0\left(p^2,m^2,M^2\right)}{4 (1-D) p^2}+\frac{\text{A}_0\left(M^2\right) \left(m^2-M^2-p^2\right)}{4 (1-D) p^2}-\frac{\text{A}_0\left(m^2\right) \left(m^2-M^2+p^2\right)}{4 (1-D) p^2}
[SPD[p], m^2, m^2] B00
-\frac{\left(4 m^2-p^2\right) \;\text{B}_0\left(p^2,m^2,m^2\right)}{4 (1-D)}-\frac{\text{A}_0\left(m^2\right)}{2 (1-D)}
[SPD[p], m^2, M^2, BReduce -> False] B00
\text{B}_{00}\left(p^2,m^2,M^2\right)
[0, m^2, m^2] B00
-\frac{m^2 \;\text{B}_0\left(0,m^2,m^2\right)}{1-D}-\frac{\text{A}_0\left(m^2\right)}{2 (1-D)}
[SmallVariable[M^2], m^2, m^2] B00
-\frac{m^2 \;\text{B}_0\left(M^2,m^2,m^2\right)}{1-D}-\frac{\text{A}_0\left(m^2\right)}{2 (1-D)}