Pullup resistors. Does it make any difference what side of the series resistor?
With the values shown, probably not. But ...



simulate this circuit &ndash; Schematic created using CircuitLab
Figure 1. The two options.

In (a) R1 and R2 form a voltage divider. When BUF1 pulls low the voltage on the input to BUF2 will be \$ \frac {R2}{R1+R2}V+ \$.

(b) avoids the problem.