string data type

Stores alphabetic, numeric, and special character data. When creating a string attribute the following validations and transformations are available to you:

Validation/Transformation	Description
Length	Maximum number of characters that can be stored in the attribute.
Unique	Globally unique attributes must be unique among all the entities in the entity type. Locally unique attributes must be unique across all the plural attributes in a single entity (e.g., a single user profile)
Required	The attribute must contain a non-null value.
Primary Key	Makes the attribute a primary key for the plural or entity type it exists in; this enables you to use API calls to target a specific record in a plural without knowing the actual identifier for that record. To set a primary key you also need the required constraint and either a unique or a locally-unique constraint.
Searchable	Indicates that the attribute can be used in a Console search (searchable attributes are typically referred to as indexed attributes).
Case Sensitive	Indicates that letter casing matters when searching for an attribute value: dog is not the same as DOG which is not the same as doG.
Write Once	Attributes that can be written to one time, then are never changed.
Convert to Uppercase	Converts all the characters in the value to their uppercase equivalent when the record is written to the database: if you enter dog your entry will be saved as DOG.
Convert to Lowercase	Converts all the characters in the value to their lowercase equivalent when the record is written to the database: if you enter DOG your entry will be saved as dog.