Comment 2 for bug 1297051

Could you provide concrete escape sequences (like an echo command, or a short text file to cat)?

I can't figure out how to test this. CSI is traditionally ESC + [. This is used e.g. to change the foreground color:
echo -e '\x1B[31mred\x1B[0m'

The CSI you're referring to seems to be an alternate encoding of the same functionality, starting with 0x9B (whose UTF-8 encoding is 0xC2 0x9B) instead of ESC [. That is:
echo -e '\xC2\x9B31mred\xC2\x9B0m'

but this doesn't work for me, not even in Putty or xterm. What am I doing wrong?

Note: gnome-terminal tries to emulate xterm. If you're asking for something that is supported by xterm, you have reasonable chances. If the feature is specific to putty, it's unlikely that your request will get implemented.