- If an explicit host is not present, then MH checks for a bang to indicate
- an explicit UUCP-style address. If so, this is noted. If not, the host is
- defaulted, typically to the local host. The lack of an explict host is
- also noted.
-
- If an explicit 822-style host is present, then MH checks to see if it
- can expand this to the official name for the host. If the hostname is
- unknown, the address is so typed.
-
- To summarize, when we're all done, here's what MH knows about the address:
-
- DUMB - type: local, uucp, or network
- host: not locally defaulted, not explicitly expanded
- everything else
-
- other - type: local, uucp, network, unknown
- everything else
- */
+/*
+** High level parsing of addresses:
+**
+** The routines in sbr/mf.c parse the syntactic representations of
+** addresses. The routines in sbr/addrsbr.c associate semantics with those
+** addresses.
+**
+** If #ifdef DUMB is in effect, a full 822-style parser is called
+** for syntax recongition. This breaks each address into its components.
+** Note however that no semantics are assumed about the parts or their
+** totality. This means that implicit hostnames aren't made explicit,
+** and explicit hostnames aren't expanded to their "official" represenations.
+**
+** If DUMB is not in effect, then this module does some
+** high-level thinking about what the addresses are.
+**
+** 1. for MMDF systems:
+**
+** string%<uucp>@<local> -> string
+**
+** 2. for non-MMDF systems:
+**
+** string@host.<uucp> -> host!string
+**
+** 3. for any system, an address interpreted relative to the local host:
+**
+** string@<uucp> -> string
+**
+** For cases (1) and (3) above, the leftmost host is extracted. If it's not
+** present, the local host is used. If the tests above fail, the address is
+** considered to be a real 822-style address.
+**
+** If an explicit host is not present, then MH checks for a bang to indicate
+** an explicit UUCP-style address. If so, this is noted. If not, the host is
+** defaulted, typically to the local host. The lack of an explict host is
+** also noted.
+**
+** If an explicit 822-style host is present, then MH checks to see if it
+** can expand this to the official name for the host. If the hostname is
+** unknown, the address is so typed.
+**
+** To summarize, when we're all done, here's what MH knows about the address:
+**
+** DUMB - type: local, uucp, or network
+** host: not locally defaulted, not explicitly expanded
+** everything else
+**
+** other - type: local, uucp, network, unknown
+** everything else
+*/