What is an $int45 interger? And its purpose?

I’m just curious as to what they use for and is there a reference list available somewhere? It would be helpful to understand the specific materials or resources they rely on for their work. Additionally, having access to a comprehensive reference list could enhance my own research efforts. If anyone has insights or knows where I might find this information, I would greatly appreciate it. Understanding their methodology could also provide valuable context for my own projects.

I was trying to run a test n ode via cpu on swagger UI. it was telling me that the fromGROUP and the toGROUP has to be in an integer.