In these cases, composite is considered a "digital" input if that helps.
Component, RGB, and PC (VGA) are analog signals.
HDMI, SDI, DVI, and composite noted above are digital inputs.
For dual input boards (TY-FB10HMD; HDMI and TY-FB9BD; composite) you may use only one of the dual inputs at a time. In other words you cannot use both inputs of a dual input board as both imputs of PIP.