/help /dll says:
Note: The data and parms variables can each hold 900 chars maximum.
Could the dll page be updated from '900 chars' to indicate the current max limit in bytes, now that Unicode means chars and bytes aren't the same thing?
Most DLL's won't care as long as the length is longer than 8292, but the info would be useful for a DLL which needs to support languages from the unicode codepoints above 2047 where each 'char' requires 3 bytes.
I've only tested 'data but not 'parms', but 900 appears to be an obsolete number from older 6.x versions which had that shorter line length. I tested to see how long of a text string of hex digits could be written into 'data' for sending back to mIRC, before it crashes mIRC. The byte length in 6.35 seems to be a few dozen bytes longer than than the 4150 limit. In 7.52 the byte length limit was somewhere around 8400 bytes, I'm assuming this extra length is for supporting multi-byte unicode characters. And now that the line length limit has doubled, the valid string bytes-length has doubled above 16k.