What does “trait A <: B” mean?

Question

In Scala, what does

trait A <: B

mean? Is it just the same as

trait A extends B

?

Edit

Answer 1

Looking at the Scala Language Specification, it seems to mean the same thing. The description for trait only mentions the trait A extends B syntax. But the Scala syntax summary uses extends and <: interchangeably for trait definitions:

TraitTemplateOpt ::= Extends TraitTemplate | [[Extends] TemplateBody]
Extends ::= ‘extends’ | ‘<:’