Keywords are ESL reserved words that, when put together, form the basis of an ESL program. Some examples of ESL keywords are variable, key, and response.

You must specify all ESL keywords in lowercase, exactly as they appear in this guide. Keywords in this guide are always shown in boldface type.

Identifiers, or user-defined names, are used to name specific parts that you define in your program. An identifier is composed of an arbitrary sequence of characters that begins with an uppercase letter.

An identifier must follow these rules:

It can contain any number of characters that fits on one line (255 characters).

It must begin with an uppercase letter (A-Z), or an extended ASCII character. Because identifiers begin with an uppercase letter, ESL can distinguish the identifiers that you define from the keywords that are predefined in the ESL language.

The remaining characters in the name can be uppercase or lowercase letters, digits, or underscore characters ( _ ), or an extended ASCII character.

The mixture of case in which you specify an identifier is significant. The identifier RedKey is not the same as the identifier Redkey, and ESL treats these as two different things.

The following are valid identifiers:

 

B 

RedKey

The_last_house_on_the_street

 

The following are invalid identifiers:

 

A*          # WRONG: contains a special character

B 5         # WRONG: contains an embedded blank

fred        # WRONG: does not begin with uppercase letter

5thStep     # WRONG: does not begin with uppercase letter 

 

It is a good practice to use easily readable, logical names that reflect the use of the entity. For example, the integer variable names "InnerLoopCounter" and "OuterLoopCounter" are more quickly understood than if they were named "I" and "J."

Once an entity is defined, you can reference it simply by its name. If the entity is an object with ancestry, there are special rules for referencing it. (See Type Conversions)