The CSYNC resource record (RFC 7477 section 2.1.1) — the child zone's request to its parent to synchronise NS A AAAA records from the child to the parent. Three fields: the child's current SOA serial, processing flags, and an NsecTypes bitmap naming the RR types to be synchronised.

                     1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                          SOA Serial                           |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|       Flags                   |            Type Bit Map       /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/                     Type Bit Map (continued)                  /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

See T_dsync for the other child-to-parent signalling RR type defined in this module.

Abstract representation of a set of RRTYPE codepoints, stored as the window-based wire-format bitmap from RFC 4034 section 4.1.2. Used by T_nsec, T_nsec3, and T_csync to carry the set of types present at the owner name.

An NsecTypes may legitimately be empty -- this is the expected encoding for an NSEC3 empty-non-terminal. With NSEC, the type bitmap is expected to include at least the NSEC type itself; that invariant is not enforced by the type.

Construction and enumeration go through IsList:

• fromList tys :: NsecTypes builds the bitmap from a list of RRTYPE values; duplicates are merged and the wire-form ordering is canonical regardless of input order. Under OverloadedLists the same input shape is just [A, AAAA, MX].
• toList bm :: [RRTYPE] enumerates the contained types in ascending wire-form order.
• (<>) unions two bitmaps; mempty is the empty bitmap.

For membership without enumerating the whole set, use hasRRtype, which goes directly to the relevant window, block and bit offset.

Construct the per-window bitmaps from a list of types.

Convert NsecTypes bitmap to an RRTYPE list

Efficient NSEC/NSEC3 type bitmap membership predicate.

The DSYNC resource record (RFC 9859) — a child zone's published endpoint for generalised DNS notifications: for a given child-side RRTYPE, it names the Dscheme (contact method, e.g. NOTIFY), the contact Word16 port number, and the Domain to address the notification to.

                     1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RRtype                        | Scheme        | Port
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                | Target ...  /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-/

See T_csync for the other child-to-parent signalling RR type defined in this module.

Target comparison and equality are case-sensitive. The Ord instance is canonical.

DSYNC scheme numbers. The Presentable instance displays the registered mnemonic of the scheme name for known types, or else just the decimal value. See the IANA registry for the known mnemonics.