What exactly is the reference DC parameter for GetWinMetaFileBits() used for?

I was under the impression that classic Win16 metafiles had no embedded size or resolution information (unless ther开发者_如何学Pythone is a METAFILEPICT header or similar) - what does GetWinMetaFileBits() use the reference DC for?

It's well documented in the SDK article:

This function converts an enhanced metafile into a Windows-format metafile so that its picture can be displayed in an application that recognizes the older format.

The system uses the reference device context to determine the resolution of the converted metafile.

and

A Windows-format metafile does not contain a comprehensive header that describes the original picture dimensions, the resolution of the device on which the picture was created, an optional text description, or an optional palette.