Specifies the maximum width of the text displayed by the text and shield symbols. Max. width is specified as a ratio to the font-size: a default value of 7 means that the text will be (roughly) 7 characters wide.
text symbol splits the text into words and then tries to fit as many words into a single line of text. If the length (in pixels) of the text exceeds the calculated max. length of the line (specified by the text-max-width property), the whole word is moved to a new line. This algorithm is repeated until all the words of the text are placed.
text-max-width : 10
specifies a text-max-width ratio of 10 (which is wider than the default value).