Allowed Characters
The strings that you pass into finAPI services may in general contain the following symbols:
A-Z, a-z, 0-9
whitespace: " " (u0020)
ampersand: "&" (u0026)
parentheses: "(" and ")"
curly braces: "{" and "}"
square bracket: "[" and "]"
dot: "."
colon: ":"
comma: ","
semi colon: ";"
question mark: "?"
exclamation mark: "!"
plus: "+"
minus: "-"
underscore: "_"
dollar: "$"
at: "@"
hash: "#"
tilde: "~"
acute: "`"
caret: "^"
euro: "€" (u20AC)
symbols with codes: from u00A1 to u00FF (see them here by "hex" from "A1" to "FF": http://www.ascii.cl/htmlcodes.htm )
symbols with codes: from u0100 to u02AF (see them here by "hex code" from "#x100;" to "#x2AF;":http://webdesign.about.com/library/bl_htmlcodes.htm )
Note that some services may allow less or more than the symbols above for certain fields. If a field deviates from the generally allowed symbols listed above, then this will be documented explicitly in the field's documentation.
For the payment initiation services, please also check Payment Data Validation as certain banks may restrict the character set in the payment payload.