\w += \p{join_control}

I notice in the proposed tr18 update at

    http://unicode.org/reports/tr18/proposed.html#Compatibility_Properties

That they've again diddled the \p{word} property for \w; they've
added \p{Join_Control} to the set of what goes into that
particular derived property.  That's just these two code points:

    U+0200C  -- GC=Cf SC=Inherited    ZERO WIDTH NON-JOINER
    U+0200D  -- GC=Cf SC=Inherited    ZERO WIDTH JOINER

This makes sense because those are two (non-Mark!) Grapheme_Extend characters,
which may in theory be needed for composing identifiers in certain scripts
(Indic, perhaps).
    
--tom

• \w += \p{join_control} by Tom Christiansen
• Re: \w += \p{join_control} by Karl Williamson