Identifiers are used to name variables and functions in MQL4.

**Constraints:**

**Maximum Length:** 63 characters.

**Allowed Characters:**

* Digits (0-9) * Latin uppercase letters (A-Z) * Latin lowercase letters (a-z) * Underscore character (_)

**First Character Restriction:** Cannot be a digit.

**Reserved Words:** Must not coincide with any reserved words in MQL4.

**Case Sensitivity:** Identifiers are case-sensitive (e.g., NAME1 and namel are different).

**Examples:** NAME1, namel, Total_5, Paper

**Related Concepts:**

[Variables](/basis/variables)

[Functions](/basis/function)

[Reserved Words](/basis/syntax/reserved)