Documentation about RGB conversion: is it sRGB? D65/2?

Hi guys, I would like to know more about the rgb conversion... what does it use right now?
Does it consider any profile?

I need a conversion from sRGB (RGB D65/2) to LAB D50/2.

I also checked that when using the transformation from RGB to XYZ, it's possible to specify the parameters for the conversion... It's the RGB profile?

