[Name] maxstale [Required] false [Type] ECMAScript Expression [Default Value] none [Valid Values] An ECMAScript expression which returns a character string in CSS2 [CSS2] format [Description] 
The character string returned must be interpreted as a time interval. This indicates that the document is willing to use content that has exceeded its expiration time (cf. 'max-age' in HTTP 1.1 [RFC2616]). If maxstale is assigned a value, then the document is willing to accept content that has exceeded its expiration time by no more than the specified number of seconds.