GameMaker is full of mysteries. For example, the manual suggests that you’re supposed to use “\xD2” for two-character sequences and “\u00D2” for four-character sequences, but turns out that it’ll accept both less and more characters for \u, so all of the following are valid:
show_debug_message("\xD2 \uD2 \u00D2 \u0000D2")
I’ll get this fixed in the next release