Hi all!
First time posting here

I've got a small question about a rogue resistor that appears on the example schematics of the HCPL3700 optocoupler, which I'd like to use as a switch.
I've managed to surmise (I think...) that the output of the IC is a Darlington/Sziklai transistor whose main function is to amplify the input current using the small current at the base from the photodiode. There's also a bypass capacitor installed (as you do), but what is the Rl resisitor between Vcc and Vout?
What's more, I've seen a version where it is connected to another capacitor (making it look like some low-pass filter, see Test circuits here:
https://www.onsemi.com/pub/Collateral/HCPL3700-D.pdf) and a version where there is no additional capacitor which made me think it was some pull-up resistor (see attached schematics, I got them from some website)
The datasheets never even mention the Rl resistor and it's making me wonder whether it's some obvious important component which any self-respecting EE will immediately recognize... making me rue the fact that I'm not a self-respecting EE

What is it for? Is it necessary? And, more importantly, how will its resistance value affect the output of the circuit?