---
title: "Serial Mask Table"
slug: "serial-mask-table"
updated: 2026-08-10T20:23:30Z
published: 2026-08-10T20:23:30Z
canonical: "help.idibilling.com/serial-mask-table"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://help.idibilling.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Serial Mask Table

| Masking element | Description |
| --- | --- |
| **0** | Digit, required. This element will accept any single digit between 0 and 9. |
| **9** | Digit or space, optional. |
| **#** | Digit or space, optional. If this position is blank in the mask, it will be rendered as a space in the Text property. Plus (+) and minus (-) signs are allowed. |
| **L** | Letter, required. Restricts input to the ASCII letters a-z and A-Z. This mask element is equivalent to [a-zA-Z] in regular expressions. |
| **?** | Letter, optional. Restricts input to the ASCII letters a-z and A-Z. This mask element is equivalent to [a-zA-Z]? in regular expressions. |
| **&** | Character, required. If the AsciiOnly property is set to true, this element behaves like the "L" element. |
| **C** | Character, optional. Any noncontrol character. If the AsciiOnly property is set to true, this element behaves like the "?" element. |
| **A** | Alphanumeric, optional. If the AsciiOnly property is set to true, the only characters it will accept are the ASCII letters a-z and A-Z. |
| **a** | Alphanumeric, optional. If the AsciiOnly property is set to true, the only characters it will accept are the ASCII letters a-z and A-Z. |
| **.** | Decimal placeholder. The actual display character used will be the decimal symbol appropriate to the format provider, as determined by the control's FormatProvider property. |
| **,** | Thousands placeholder. The actual display character used will be the thousands placeholder appropriate to the format provider, as determined by the control's FormatProvider property. |
| **:** | Time separator. The actual display character used will be the time symbol appropriate to the format provider, as determined by the control's FormatProvider property. |
| **/** | Date separator. The actual display character used will be the date symbol appropriate to the format provider, as determined by the control's FormatProvider property. |
| **$** | Currency symbol. The actual character displayed will be the currency symbol appropriate to the format provider, as determined by the control's FormatProvider property. |
| **<** | Shift down. Converts all characters that follow to lower case. |
| **>** | Shift up. Converts all characters that follow to upper case. |
| **\|** | Disable a previous shift up or shift down. |
| **\** | Escape. Escapes a mask character, turning it into a literal. "\\" is the escape sequence for a backslash. |
| All other characters | Literals. All nonmask elements will appear as themselves within MaskedTextBox. Literals always occupy a static position in the mask at run time, and cannot be moved or deleted by the user. |