According to "vttest", it is legitimate to embed control characters inside of an escape sequence (although I'm not sure why that makes sense). Nevertheless, I'm coding to accommodate that in my emulator. So my question is this... Are all control characters valid inside an escape sequence or just a select few? The reason I ask is because the the string which accompanies the OSC "set window title" sequence is often terminated by 0x7 (bell) so that seems to be an issue. In the "vttest" scenario, only "backspace" and "vertical tab" are injected into the escape string. Is that because they're the only two that are permissible?