Interactive Disassembler

Read this here: https://www.hex-rays.com/products/ida/tech/flirt/index.shtml

I think they overhauled the FLIRT system in a recent version of IDA. Overall it works pretty well, but there is a lot of room for improvement. It's kind of like "finding a needle in a haystack".

It's annoying when the FLIRT names so many false positives. It assumes a match on just a partial signature match from the first so many bytes of a function. Note depending on the build options library functions can be static, using a DLL, or inlined, plus the generated code can depend on optimization settings (thus signitures not matching). There is probably a lot of room for improvement that uses a more exacting system other then FLIRT.

Also related that might be interesting is "GraphSlick" that can find inlined functions:

"This plugin automates detection of inlined functions. It highlights similar groups of nodes and allows you to group them, simplifying complex functions. The authors provide an accompanying presentation which explains the algorithms behind the plugin and shows sample use cases."

https://github.com/nihilus/graphslick

You are right, it means this parameter is not stored in any register. It is stored on stack instead. First part (0) is an offset into arguments area of the stack, second part (16) is the argument's size.

EDIT: the very first part of this (0010) is the hexadecimal argument size, while the second part (rsi or ^0.16) is the so-called argument location. I don't know if it is actually documented anywhere as a thing but this doc: https://hex-rays.com/products/ida/support/idadoc/1492.shtml - describes scattered arguments including this syntax in more details.