Render target and HDR maximum value

Hello!
I’m trying to use Render target for my calculations
But I think I run into limits by channels and that the most interesting for different channels is a different limit. How is this possible?)
What is the maximum number that can be written in the RGB channels separately?

And

How do I write data to an alpha channel?
Because the emmisive output is written only by the RGB

Render target format dictates the range of values, that you can store. If i’m not mistaken, HDR refers to R16G16B16A16 format should give you values up to 65k for each channel.

There was a tickbox in material settings, that allows you to output alpha with emissive I think.

Thanks for the answer. Unfortunately I did not find the tickbox - which would be responsible for the alpha channel. Alpha channel is 25% of the data Which I really lack for a full calculation. I would not like to have a additional Render target for these purposes