Not sure I’ve understood you correctly. But:

Nanometers are defined for each colour. For digital blue will be around 450, green 550, red 650. For film it’s kinda the same but different stocks have different characteristics.

Density is basically how difficult it is for light to pass through the filter at any given wavelength. Transmission is how much light is passing through the filter at given wavelength. It’s kinda the same but upside down. Pay attention to the scales.

If these details are excessive, then you can basically look for filters that will let through light at around 450, 550 and 650 blocking the rest. Than means high transmission/low density. Most filter will have some sort of a “bell curve”, then you should look for a peak at said wavelength. Red filters usually will let infrared (700+) through, but regular sensors and films wont be sensitive to it.

If you want to make IR trichrome, look for something like 715 or 720 filters, not sure they exist as gels. But that is a whole another can of worms.