3.5 Key-Value Format

Columns that provide Key-Value information are often used in place of separate columns for enumerating data which would be inherently sparse and/or without predetermined keys. This consolidates related information and provides more consistency in the schema. Key-value pairs are also referred to as name-value pairs, attribute-value pairs, or field-value pairs.

All key-value related columns defined in the FOCUS specification MUST follow the key-value formatting requirements listed below.

Rules and formatting requirements for columns appearing in a FOCUS dataset that convey data as key-value pairs.

• Key-Value Format columns MUST contain a serialized JSON string, consistent with the ECMA 404 definition of an object.
• Keys in a key-value pair MUST be unique within an object.
• Values in a key-value pair MUST be one of the following types: number, string, true, false, or null.
• Values in a key-value pair MUST NOT be an object or an array.

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