code optimization

[Julien Bessiere]

Hi,
i'm working with fgs-mapserver and php-mapscript.
i was wondering if i'd rather develop the php code using the php class or on the
contrary develop the map file.
For example, i want to display a layer with level line. I could build the class
with php or i could write several class in my map file, someting like:
	CLASS
		NAME "201-300"
		EXPRESSION (([ELEVAC]> 200) and ([ELEVAC]< 301))
          STYLE
			SIZE 1
			COLOR 100 40 0
          END
        END

what's the best way?

thx for your advice.

julien