As researchers in web localisation, web accessibility and controlled-language (CL) software, we have noticed a gap in the way the three can be brought together in mutually advantageous ways. Localisation in general has shown little awareness of accessibility matters. The different accessibility checkers that are available are seldom used by localisers and web accessibility regulatory bodies and assessment tools have traditionally been very vague about language-related requirements. In this paper, we explore a linguistic approach based on semiotics and communicative value to help localisers analyse the accessibility needs of web content (and, in particular, nonverbal elements such as images) by means of an evaluation methodology based on controlled-language rules integrated in a content authoring tool.