Scheme, as related to the URI format, is the part of a URI that indicates the protocol. For example, the scheme in the URI sip:firstname.lastname@example.org is “sip.”
Relevant NENA Documents
Note: To find and download the document, copy the document number (like NENA-STA-010) from below and search the NENA Standards and Documents page.
NENA-STA-010, NENA i3 Standard for Next Generation 9-1-1