I am conducting a survey to determine what is the typical 
     configuration of 20 (19.7) mil pitch surface mount pads.
     
     The questions:
        1) What is the typical bottom of pad measurement & requirement?
        2) What is the associated top of pad measurement & requirement?
        3) What dimension is the artwork plotted for the pad?
        4) Do these pads have soldermask webs (dams) between them? What     
           size is web and what is the spacing (web to pad) on the artwork?
     
     Any additional help and information would be appreciated.