Mesa Confusion Sinking Vs Sourcing

Hello, The more I read the more confused I get so I will seek for help here.

I want to build a cnc mill that is 3 axis for now (would like the option to move to a 4 axis in the future)  I would also like to set the spindle speed via gcode (mitsubishi servo)

I currently have a
2x ClearPath CPM-SDSK-3421S-RLN
1x ClearPath CPM-SDSK-3432S-RLN
1x ClearPath Brake 24v MPC034-24-003-T
3x ipc5 power supplies and all the power/data cables
1x Intel NUC Core i5-9300H, 16GB RAM, 512GB PCIe SSD

Is the 7I76 cards what I need to make this work or is there a better one?
If so can you please tell me the difference between the 7I76E (sourcing output) and 7I76EU (universal output)?

Sinking or sourcing only applies to the 12/24V digital outputs
on the 7I76/7I76EU/ It likely makes no difference in your setup at all.

Thank you for the reply. You mean for things like limit switches? A sinking would mean that I give it ground when I want the limit switch to be triggered?

No, a sinking input needs as sourcing driver.

so say:

+24V --> switch1 --> switch2 --> sinking_input

or PNP prox --> sinking input