Hal,
Interesting post. Sounds like Fromm is saying the linen side does have an abrasive in it which now answers the question as to whether the linen side has any effect in sharpening.
They seem to be saying the leather side is simply more coarse than the top grain leathers like the #361 and others so this would be an intermediary strop.
The linen side of both my 827 and my 361 look identical and so did the 206 I sold so I wonder if all their linem strops have abrasive in them.
Tony