8.6 Syntax

[388] \Uhhhhhhhh – Reserved syntax for codepoints above BMP Incompatibility versus \U (≡ “U”)

[388] \xhh – Now limited to 2 hex digits max Incompatibility versus \xhhhhHH (≡ “\xHH”)

[388] Treat \4dd…\7dd (consistently) as “\04” ”dd”… ”\07” ”dd” Inconsistent before.

\701 ≡ \301 (Tcl parser strips bit 9)

\701 ≡ \u01c1 (regexp engine handling)

Incompatible now, of course.