The following conventions apply to the names of all definable objects within ABAP programs, such as data types, data objects, classes, macros, or
procedures:
A name can be up to 30 characters in length.
Permitted characters are letters from "A" to "Z", digits from "0" to "9", and underscores (_).
The name must start with a letter or an underscore (_). Only outside of ABAP objects can the name also start with a different character.
The name can have a namespace prefix. A namespace prefix consists of at least three characters that are enclosed by two forward slashes
(/.../). The entire length of prefix and name cannot exceed 30 characters.
The names of predefined ABAP types or predefined data objects cannot be used for data types or data objects.
The use of IDs that are reserved for ABAP words and so on for custom definitions is not actually forbidden, but is strongly advised against.
Field symbols are special because their names have to be enclosed in angle brackets
(<...>). The angle brackets are a part of the name, which means that a field symbol could potentially be called <> (but this is not recommended).
All types possible in ABAP are in a namespace. Data types and object types do not have separate
namespaces. A global class, for example, cannot be created with a name that is already being used for a data type in ABAP Dictionary.
The naming conventions presented here must be followed. They are not checked in full by the syntax check, but they must not be broken more than absolutely necessary.
The program DEMO_CHARACTERS_IN_ABAP_NAMES demonstrates how these checks run in the current system.
Namespaces
Outside of class declarations, different objects have separate namespaces, so it is possible that data
types, data objects or procedures can have the same name. Classes and interfaces thus lie within the
same namespace as data types. The namespace is valid for the respective context. Within a context, the
names of the same objects must be unique. For example, there can only be one subroutine with the same name in an ABAP program and only one function module with the same name in the entire
AS ABAP.
Within a class declaration, the name of every class component (data type, attribute, method, event, or alias name) must be unique.
Reserved Names
The following names are reserved and cannot be used in any other declarations:
Self-defined data types cannot have the name of a
built-in ABAP type. This applies to type definitions in the ABAP language and in
ABAP Dictionary.
The name of a structure component cannot be the name of the
pseudo componenttable_line. This applies to type definitions in ABAP and in
ABAP Dictionary as well as to data declarations and when creating data objects in ABAP.
A secondary table
key of an internal table cannot have the predefined names primary_key or loop_key.