Meanings This is where a teacher can explore what meanings there are in texts, but again, from the position of a questioner and challenger.
Purposes This encourages teachers and students to question whether a text has relevance, to its own time and to today.
Values and Attitudes and Assumptions This is again where the student must challenge the text, examining the values and attitudes through the prism of assumptions. The word assumption tells us that the author (composer!) has made assumptions that he/she "takes for granted" and that are "embedded" in the text(BOS definitions). It is thus our job to be detectives and expose these cultural assumptions. (eg. "Aha! This writer is a feminist post modernist with structuralist leanings", or "Ah Harper Lee assumes that her readers have some idea about the American Civil War").
Language - This is telling us the crucial role language has in delivering us the messages, values and assumptions. This is why language must be broken up in a microcosmic way - deconstructed in order to demonstrate just how a composer embeds their assumptions and create their messages.
Studying Texts from Various Perspectives Cultural Products This tells us that texts are cultural products ie. a product from a "particular people or group" (BOS definition of culture) and that we need to see them in this light. This is in direct contrast with the "canon" approach to literature study, which encouraged students to see the universal messages and themes in texts. This means that Shakespeare turns from being a messenger through the ages about such issues as death and lifes purpose, but into an Elizabethan play hawker trying to please his audiences. In this same light, Harper Lee is no longer a timeless communicator on prejudice and racism and more the composer of a text that helped to inspire the African American Rights movement of the 1950s and 1960s.
The BOS Syllabus Definition
(my bold text)
Critical literacy: The ability to question, challenge and evaluate the meanings and purposes of texts. It involves an understanding of the ways in which values and attitudes are communicated through language, including how subject matter, point of view and language embody assumptions about issues such as gender, ethnicity and class. A critical literacy approach to teaching English has students composing, responding to, analysing and evaluating written, spoken, visual and multimedia texts from various perspectives in order to learn how they operate as cultural products.
The placement of Question, Challenge, then Evaluate indicates that the student needs to attack a text from a negative viewpoint (a questioner, a challenger) before they can even start to evaluate the meanings and purposes of texts.