# How to Enter an Identifier An identifier is a name which starts with a letter and contains only letters and digits. The list of allowed characters is specified in config file [IDA.CFG](/9.0/user-guide/configuration/configuration-files.md). All names are case-sensitive. Maximal length of a name is specified in the configuration file too: ``` MAX_NAME_LENGTH=120 // Maximal length of new names ``` Default is 120. Some assemblers have a shorter name length limit, beware! IDA will warn you if you enter an illegal name. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.hex-rays.com/9.0/user-guide/disassembler/navigation/how-to-enter-an-identifier.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.