identifiers.summary.txt

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                                  ┃   IDENTIFIERS_SUMMARY   ┃
                                  ┗━━━━━━━━━━━━━━━━━━━━━━━━━┛

USE CASES ==>                     #SGML:                              publicid/FPI
                                  #Full content:                      data URI
                                  #Decentralized:
                                  #  - same content -> same resource: NI
                                  #  - otherwise:                     UUID
                                  #Human-friendly:
                                  #  - easy to read|understand:       tag
                                  #  - easy to type or spell out:     NI (nih)
                                  #Efficient:                         URL or no URI
                                  #Registered:
                                  #  - with metadata:                 DOI or OID
                                  #  - otherwise:                     URN

NO URI ==>                        #E.g. database incremental ID (as opposed to using URI)
                                  #  - more efficient (e.g. smaller) but application-specific
                                  #Can also store URI shortcut, i.e. URI without URI scheme or namespace:
                                  #  - URN: only NSS
                                  #  - tag: only DATE:TAG
                                  #  - UUID: non-URI format
                                  #  - NI: only [ALGO;]HASH

URL ==>                           #Using location as identification:
                                  #  - does not require resolution to retrieve location (less round-trips)
                                  #  - but couples location with identification

CROSS-IDENTIFIERS ==>             #Can:
                                  #  - publicid/FPI, OID, UUID -> URN
                                  #  - UUID                    -> OID

+--------------+---------------------------------------------------+-------------------+-------------------+-------------------+-----------------+--------------------------------------+------------------+
| NAME         | SYNTAX                                            | FORMATS           | NAMESPACE         | HUMAN-FRIENDLY    | LOCATION        | METADATA                             | USAGES           |
+--------------+---------------------------------------------------+-------------------+-------------------+-------------------+-----------------+--------------------------------------+------------------+
| URN          | urn:NID:NSS                                       | URI               | REGISTERED_ID     | namespace-only    | yes             | no                                   | books, texts     |
+--------------+---------------------------------------------------+-------------------+-------------------+-------------------+-----------------+--------------------------------------+------------------+
| DOI          | doi:NAMESPACE/ID                                  | URI               | REGISTERED_ID     | namespace-only    | Handle system   | yes (using resolution)               | publishing       |
+--------------+---------------------------------------------------+-------------------+-------------------+-------------------+-----------------+--------------------------------------+------------------+
| OID          | NUM.NUM2...                                       | [non-]URI, binary | REGISTERED_ID     | no                | yes             | description, ctime (using resolution)| anything         |
+--------------+---------------------------------------------------+-------------------+-------------------+-------------------+-----------------+--------------------------------------+------------------+
| publicid/FPI | PREFIX//OWNER//CLASS DESCRIPTION//LANG[//VERSION] | non-URI           | DOMAIN            | good but verbose  | no              | description, lang, version           | SGML             |
+--------------+---------------------------------------------------+-------------------+-------------------+-------------------+-----------------+--------------------------------------+------------------+
| tag          | tag:DOMAIN,DATE:TAG                               | URI               | DOMAIN            | very good         | no              | date                                 |                  |
+--------------+---------------------------------------------------+-------------------+-------------------+-------------------+-----------------+--------------------------------------+------------------+
| UUID         | AAAAAAAA-BBBB-CDDD-EEFF-GGGGGGGGGGGG              | [non-]URI, binary | random [+ DOMAIN] | no                | no              | no                                   |                  |
+--------------+---------------------------------------------------+-------------------+-------------------+-------------------+-----------------+--------------------------------------+------------------+
| NI           | ni://[AUTHORITY]/ALGO;HASH[?VAR=VAL&...]          | URI, binary       | content checksum  | easy to spell out | well known URIs | authority, MIME, anything            |                  |
+--------------+---------------------------------------------------+-------------------+-------------------+-------------------+-----------------+--------------------------------------+------------------+
| data URI     | data:[MIME][;charset=CHARSET][;base64],CODE       | URI               | content full      | no                | not needed      | no                                   |                  |
+--------------+---------------------------------------------------+-------------------+-------------------+-------------------+-----------------+--------------------------------------+------------------+