1. A computer-implemented process control display system for producing a graphical display of alphanumeric process control statements corresponding to a process being controlled, the process control statements comprising a set of lexical units grouped in a syntactic relationship defined by a predetermined grammar with at least a subset of the lexical units being capable of representing data, the process control display system comprising: means for supplying a process control statement to be displayed; statement analyzer means for generating a parse tree corresponding to the process control statement to be displayed; means for producing a graphical display window; means for establishing a predefined set of graphical icons for representing at least a portion of said lexical units; display generation means in communication with said parse tree for placing selected ones of said predefined set of graphical icons in said display window in a spatial relationship corresponding to the syntactic relationship of said lexica units which make up said process control statement to be displayed; means for supplying data from the process being controlled, said data corresponding to at least one of said lexical units of said process control statement to be displayed; evaluation means responsive to the syntactic relationship defined by said process control statement to be displayed, for establishing visual quality of said selected graphical icons in said display window based on said supplied data, whereby at least a first condition may be visually distinguished from a second condition on the basis of its visual quality.