# Allowed characters

Client supplied FIX identifier field values must contain between at least one and up to one hundred allowed characters.

Any exchange-bound message containing an invalid identifier will be rejected.

Client supplied identifier values should match against this PCRE regular expression: <br/>
`[:\-_\.#a-zA-Z0-9]{1,100}`

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### CHARACTER TABLE

| Characters | Description                   | ASCII Codes (Dec) |
| :--------: | ----------------------------- | ----------------- |
|   `A-Z`    | Uppercase letters A through Z | 65 – 90           |
|   `a-z`    | Lowercase letters a through z | 97 – 122          |
|   `0-9`    | Digits                        | 48 – 57           |
|    `#`     | Hash, octothorpe, number sign | 35                |
|    `-`     | Hyphen                        | 45                |
|    `.`     | Period                        | 46                |
|    `:`     | Colon                         | 58                |
|    `_`     | Underscore                    | 95                |