This screenshot is an example of using standard input and output for the tidy.exe program:

http://www.emeditor.com/images/emeditor9_tool_prop_e.png

(in the "New External Tools" section of the EmEditor Professional 9 feature page: http://www.emeditor.com/modules/feature1/rewrite/tc_35.html )

The standard input/output is used only if the external program supports standard input/output. Most Windows programs don't utilize standard input/output, but console programs (most programs run from the Command Prompt window) may use standard input/output. You can get more information by searching the Internet with "standard input or output".

Thanks!

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Yutaka Emura
Developer of EmEditor
http://www.emeditor.com/