Can LOINC be defined as a Controlled Terminology?

I noticed you have a set of instructions for configuring MedDRA.  But how would we add LOINC?

The example for the UNII dictionary only shows two columns.  For LOINC it needs several variables whose values confer uniqueness to the row. For example, a row-uniqueness is usually determined by the combination of LOINC NUM, COMPONENT, PROPERTY, SYSTEM and METHOD.

Thanks

Joyce