Annexes are normally used to provide technical or other information which it would be difficult to include in the main body of an instrument. Ten Conventions, one Protocol and 15 Recommendations contain annexes. These are placed at the end of the instruments, they are an integral part of those instruments and vary in form and content depending on the subject matter. 

As regards amendments to annexes, three different procedures are provided for in the relevant instruments. Some provide that the amendment can be made by future adoption or revision of any Convention or Recommendation through a two-thirds majority decision of the Conference. The MLC, 2006 and Conventions Nos 185 and 188 provide for a simplified or tacit amendment process, whereby the acceptance of entry into force of duly adopted amendments to annexes is implicit in the absence of a written notice to the contrary. Finally, Recommendation No. 194 provides for the amendment of the list of occupational diseases contained in its annex through a tripartite meeting of experts convened by the Governing Body which should approve the amended list before it is communicated to Members.

Annexes have a certain interpretative value for determining the meaning of a particular provision in its context and in the light of its object and purpose.