The GRL is sub-divided in two parts:
Part 1 contains chemically defined substances (CDS) and Part 2 contains source materials and / or natural complex substances (NCS).

The GRL is subject to regular updates.

Generally, materials that have been included in the Part 1 of the IOFI GRL have been reviewed and determined to be safe for flavor use in food by one or more of the following competent risk assessment bodies, the European Food Safety Authority (EFSA), the Council of Europe (CoE), the U.S. Food and Drug Administration (FDA), the Expert Panel of the Flavor and Extract Manufacturers Association of the United States (FEMA Expert Panel), the Joint FAO/WHO Expert Committee on Food Additives (JECFA) or the Japanese Food Safety Commission (FSC). While the inclusion of a flavoring substance in the Part 1 of the IOFI GRL supports the conclusion that it can be safely added to food for its intended use as flavouring substance, it does not in and of itself confer regulatory authority to use in any specific regulatory jurisdiction. Regulatory authority for the market of intended sale must be separately determined.

Materials of plant or animal origin (i.e., source materials) may be used to produce flavorings. The preparations derived from these source materials (e.g., essential oils, essences, extractives, etc.) are referred to as natural complex substances or natural flavoring complexes. On Part 2 of the IOFI GRL, source materials and/or natural complex substances that have undergone a safety evaluation by the FEMA Expert Panel and/or have been accepted for use by the US FDA, the Council of Europe and/or any other national or regional authority are provided.