On this page, I will introduce a selector circuit which chooses one channel from four channels which are composed of 4 bits.
Either input is chosen from four channels by the 2-bit selection signal and is output.

Pin lock isn't specified.
As the device, it deals with CPLD(XC9536-PC44).

Source code and Explanation Fitting report

Operating state table

Input		Output
SEL(1)	SEL(0)	Q3 - Q0
0	0	Q = A
0	1	Q = B
1	0	Q = C
1	1	Q = D