Well that didn't work. I must have done something wrong. This is what I did.

Click the little 'Picture' icon above the edit box - an Insert Image box appears.

Click the 'Choose Files' button, select 'All files (*.*) from the drop down bottom right of the 'Open' dialog so text files show up, scroll down and select my text file, click 'Open'...

The 'Open' dialog  and 'Insert Image' box simply vanish 

(I did mention that I'm a professional idiot tester, didn't I ? If it's possible to do something wrong by following the instructions I'll do it...)

(I'm using Edge)

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The 3Dcheapskate (also available in DAZ and HiveWire3D flavours) occasionally posts sensible stuff. Usually by accident.
And it usually uses Poser 11, with units set to inches. Except when it's using Poser 6 or PP2014, or when its units are set to PNU.