Some PIs may have affiliations with more than one ALMA Executive or region (EA, NA, EU, or Chile), either by virtue of a joint affiliation with institutes in different regions, or through Executive agreements (e.g., Taiwanese investigators, who have affiliations with both EA and NA). 

For proposal submission, users from Taiwan (which is affiliated with both EA and NA) will be able to select either an EA, NA or combined EA/NA affiliation in the OT on a proposal-by-proposal basis (see ALMA Observing Tool User Manual).

For more information, please view the Knowledgebase article "What is the "Choose ARC" entry on the registration page?"