The remaining unexplained entry box on the Measurements dialog allows the entry of a multiplier number:
The multiplier allows the user to break out of the Punch! 500' x 500' maximal plan size (now 1000' x 1000', in the Topography Designer), into whatever domain is useful for the extended task that needs to be planned in Punch!. City and park planning are possible with this technique, and Dimensions in Detail supplies the plans through Punch!.
The idea is that if the designer supplies a multiplier other then the default value of 1.0 then all measurements on the plan are multiplied by that number. Dimensions in Detail displays those changed values and they are, of course, available for export and printing operations through Dimensions in Detail. Supplying a multiplier of 10.0, for example, allows the Punch! plan to be used to simulate an area of close to a square mile in extent. The scale and all the dimensional values will reflect the modified lengths. The model pictured was captured at a multiplier value of 12.0.
Of course, the maxim of TANSTAAFL (There Ain't No Such Thing As A Free Lunch) is still alive and applicable. There are several problems with applying a multiplier that have to be worked with, because Punch! doesn't support the use of a multiplier. As a result, the actual construction of the model, done in Punch!, has to be executed with units scaled in the designer's head or a handy calculator. Say you were using a multiplier of twelve to model an area larger than a square mile. If you wished to add a structure to the plan that was 30' x 20', the dimensions that you would need to enter into Punch! would be 30" x 20" instead. This goes for all dimensions, horizontal and vertical. It also includes such things as wall thicknesses, floor thicknesses, and all sorts of other measurements. A twelve inch thick floor would be modelled as 1". This is pretty convenient for a multiplier of 12, but might get pretty bloody for a factor like 5, since Punch! displays feet and inches.
Some measurements in Punch! cannot be adjusted, such as the thickness of roof pieces and the like. There is no way to avoid having an especially thick roof in these cases. This would probably be a big handicap, except that designers who want to to use this feature may well not care about individual structures, but rather groupings of buildings.
There are other problems related to the same effect. Plants will be the multiplier factor too large. Walk-through speeds will be faster than normally experienced by the factor of the multiplier. Textures with patterns on them (and that is what textures are for, basically), when applied to a surface, will be the multiplier factor too small. Roofing shingles may look to be thumbnail size, for example. For the most part, abandoning textures for simple colors might be the best bet. The granularity of the topography, normally executed on 3' x 3' squares, will go to 36' x 36' squares for the multiplier = 12 case.
For certain users that only need a small boost (say, factors up to, perhaps, 1.5) many of the differences will be negligible. For them the advantages of being able to plan their entire space in a single Punch! file may be worth the hassle. In any case, Dimensions in Detail will support the drawings that are the final outcome.

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