I don't think there's an agreed-upon standard. There's a couple of 'conventions' to avoid collisions between types and names, one would be PascalCase for types

I don't think there's an agreed-upon standard. There's a couple of 'conventions' to avoid collisions between types and names, one would be PascalCase for types and camelCase for anything else, another is using snake_case for both, but use the _t postfix for types (which is a bit shunned upon because the _t postfix is reserved by POSIX - but not the C standard).