If you have replaced some referenced graphics with others, and your graphics are in several formats, such as mostly GIF plus some JPEG and some PNG, you can do the following:
1. Identify the “main” format by specifying its file extension; for example:
2. Specify file extensions for the other formats as exceptions:
; old suffix = new suffix, overrides [Graphics]GraphSuffix
; jpg=jpg leaves all .jpgs alone even if GraphSuffix=gif
; wmf=png .wmfs are made into .pngs using a third-party tool
3. Specify file names with extensions for any individual exceptions (see §31.3.1.2 Substituting graphics files for HTML):