run without
change, on a time scale of years, including in production environments such as
Google App Engine. Similarly, people should be able to write books about Go, be
able to say which version of Go the book is describing, and have that version
number still be meaningful much later.
</p>

<p>
Code that compiles in Go 1 should, with few exceptions, continue to compile and
run throughout the lifetime of that version, even as we issue updates and bug
fixes such as Go version 1.1, 1.2, and so on. Other than