This is the "External Reference Repeater" template.
It should be called in the following format:
{{External Reference Repeater
|External Source=
|External Accession ID=
}}
Edit the page to see the template text.
{{#set_internal:is_External_Reference
|from_External_Source={{{External Source|}}}
|has_External_Accession_ID={{{External Accession ID|}}}
}}
{| class="wikitable"
! Source
| [[From External Source::{{{External Source|}}}]]
|-
! Accession ID
| [[Has External Accession ID::{{{External Accession ID|}}}]]
|}