I have a question about this fiddle:

1) it would be better to make charset a `VarChar`, due to ooold history of SQL standard and pre-SQL formats (like DBF), system tables in Firebird are traditionally space-padded `CHAR`, but when exporting that makes a veeeery wide text. Most client application right-trim `CHAR` type columns automatically, but db fiddle seems to avoid doing so. 

Then the typecast is needed - see https://dbfiddle.uk/?rdbms=firebird_3.0&fiddle=50247a701bbb634931cd1f9008190515

Or maybe auto-trimming is to be implemented.

2) after "7 rows affected" line in Markdown export there is an extra empty line added, this looks bad, and it seems it is due to omitting comment-bracket. See rev.#2 of my answer at https://stackoverflow.com/revisions/64872410/2

<>https://dbfiddle.uk?rdbms=firebird_3.0&fiddle=f48e769ee0b15ea8a944922ed7bb384a