except.txt lists features that may disappear without breaking true
compatibility.

Starting with go1.19.txt, each API feature line must end in "#nnnnn"
giving the GitHub issue number of the proposal issue that accepted
the new API. This helps with our end-of-cycle audit of new APIs.
The same requirement applies to next/* (described below), which will
become a go1.XX.txt for XX >= 19.

[runtime/metrics](/pkg/runtime/metrics/) counter
named `/godebug/non-default-behavior/<name>:events`
that counts the number of times a particular program's
behavior has changed based on a non-default value
for that setting.
For example, when `GODEBUG=http2client=0` is set,
`/godebug/non-default-behavior/http2client:events`
counts the number of HTTP transports that the program
has configured without HTTP/2 support.

## Default GODEBUG Values {#default}

The [Repeat] function returns a new slice that repeats the

The [RuneLen] function returns the number of 16-bit words in
the UTF-16 encoding of the rune. It returns -1 if the rune

+ If there is a corresponding issue, add either `Fixes #1234` or `Updates #1234`
  (the latter if this is not a complete fix) to this comment
+ If referring to a repo other than `golang/go` you can use the
  `owner/repo#issue_number` syntax: `Fixes golang/tools#1234`
+ We do not use Signed-off-by lines in Go. Please don't add them.
  Our Gerrit server & GitHub bots enforce CLA compliance instead.

Files in this repo's `api/next` directory must have corresponding files in
`doc/next/*stdlib/*minor`.
The files should be in the subdirectory for the package with the new
API, and should be named after the issue number of the API proposal.
For example, if the directory `6-stdlib/99-minor` is present,
then an `api/next` file with the line

    pkg net/http, function F #12345

pkg debug/dwarf, type UintType struct, embedded BasicType
pkg debug/dwarf, type VoidType struct
pkg debug/dwarf, type VoidType struct, embedded CommonType
pkg debug/elf, const ARM_MAGIC_TRAMP_NUMBER ideal-int
pkg debug/elf, const DF_BIND_NOW DynFlag
pkg debug/elf, const DF_ORIGIN DynFlag
pkg debug/elf, const DF_STATIC_TLS DynFlag
pkg debug/elf, const DF_SYMBOLIC DynFlag
pkg debug/elf, const DF_TEXTREL DynFlag

pkg crypto/x509, type RevocationList struct
pkg crypto/x509, type RevocationList struct, ExtraExtensions []pkix.Extension
pkg crypto/x509, type RevocationList struct, NextUpdate time.Time
pkg crypto/x509, type RevocationList struct, Number *big.Int
pkg crypto/x509, type RevocationList struct, RevokedCertificates []pkix.RevokedCertificate
pkg crypto/x509, type RevocationList struct, SignatureAlgorithm SignatureAlgorithm

pkg encoding/json, method (*Decoder) Buffered() io.Reader
pkg encoding/json, method (*Decoder) UseNumber()
pkg encoding/json, method (Number) Float64() (float64, error)
pkg encoding/json, method (Number) Int64() (int64, error)
pkg encoding/json, method (Number) String() string
pkg encoding/json, type Number string
pkg encoding/xml, const Header = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"

pkg go/doc/comment, type List struct, Items []*ListItem #51082
pkg go/doc/comment, type ListItem struct #51082
pkg go/doc/comment, type ListItem struct, Content []Block #51082
pkg go/doc/comment, type ListItem struct, Number string #51082
pkg go/doc/comment, type Paragraph struct #51082
pkg go/doc/comment, type Paragraph struct, Text []Text #51082
pkg go/doc/comment, type Parser struct #51082