foo
bar
foo
bar
  • When allowing URLs to be provided (e.g. for links), the scheme of each URL also needs to be explicitly safelisted, as there are many schemes that can be abused. The most prominent example is "javascript:", but user agents can implement (and indeed, have historically implemented) others.

    • For example, this specification disallows nesting a section element inside a kbd element, since it is highly unlikely for an author to indicate that an entire section should be keyed in.

    A QName in the node test is expanded into an expanded-name using the namespace declarations from the expression context. If the QName has a prefix, then there must be a namespace declaration for this prefix in the expression context, and the corresponding namespace URI is the one that is associated with this prefix. It is an error if the QName has a prefix for which there is no namespace declaration in the expression context.

  • If the character indicated by position is not an ASCII digit, then return an error.

  • Collect a sequence of code points that are ASCII digits from input given position, and interpret the resulting sequence as a base-ten integer. Let value be that integer.

  • Either a U+002B PLUS SIGN character (+) or, if the time-zone offset is not zero, a U+002D HYPHEN-MINUS character (-), representing the sign of the time-zone offset
    • Durations

    A duration consists of a number of seconds.

    Since months and seconds are not comparable (a month is not a precise number of seconds, but is instead a period whose exact length depends on the precise day from which it is measured) a duration as defined in this specification cannot include months (or years, which are equivalent to twelve months). Only durations that describe a specific number of seconds can be described.

    A string is a valid duration string representing a duration t if it consists of either of the following: