UNIT                                                                Menu: SCRN
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Changes the working unit and sets other associated parameters.

         1. (CHAR) NEW unit: m-meter, c-centimeter, l-millimeter, f-feet
      if `m', `c', or `l' are selected:
         2. (NUM) metric dimensions format (10-13, 20-23, 30-33, 43, 44)
                                                            <curr. format>
      if `f' is selected:
         2. (CHAR) x,y,z display format (1,2,3,4,5) <curr.format>
         3. (CHAR) scale display format (1,2,3,4,5) <curr.format>
         4. (NUM) feet dimensions format (-10,-11,-12,-20,-21,-22,-23,-30)
                                                               <curr.format>
      for all units:
         5. (NUM) solid tolerance (range in current unit) <curr.tolerance>
         6. (NUM) reference scale (0.01-100000) <curr.ref.scale>
         7. (NUM) size of arc segment in ref. scale 1: curr. ref. scale
                                       (range in current unit) <curr.arcsize>
         8. (NUM) minimum and maximum number of segments in an arc
                                                  (range: 5-500) <curr.range>
      if grid is on:
         9. (NUM) grid interval (min. value in curr. unit , 0-to switch off)

Description

This command changes the working unit and sets all the parameters associated
with it.
Enter the new working unit.  The options are meters, centimeters, millimeters
or feet.

If meters, centimeters or millimeters are selected, enter the format code for
the metric dimension.

Format codes greater than 0 indicate that the units are metric.  The first
digit represents the specific unit `1' for meters, `2' for centimeters, `3'
for millimeters.  The second digit represents the number of digits appearing
after the decimal point.  Format codes 43 and 44 display the dimension text in
meters, with the millimeters (and mm in format 44) typed in superscript.

The following table shows how a metric dimension is displayed using the
various format codes:

         Format   Value
         Code     (in meters)    Text

         10      1.234           1
         11      1.234           1.2
         12      1.234           1.23
         13      1.234           1.234
         20      1.234           123
         21      1.234           123.4
         22      1.2345          123.45
         23      1.23456         123.456
         30      1.23456         1234
         31      1.23456         1234.6 (rounded up)
         32      1.23456         1234.56
         33      1.234567        1234.567
         43      1.234           1.234
         44      1.2345          1.2345

If feet are selected, define the display format for the x,y,z values line and
the scale on the top screen.  There are 5 format options:

1 Feet in decimal format, e.g., 1.5'.
2 Feet and inches, with inches in decimal format, e.g.,1' 6.5".
3 Feet and inches, with inches in fraction format, e.g.,1' 6-" (accuracy to ").
4 This format is the same as option 3, but if a higher degree of accuracy
  is necessary, option 1 is selected by the program.
5 This format is the same as option 3, but if a higher degree of accuracy
  is necessary, option 2 is selected by the program.

Note that a metric scale of 96 (1:96) will be displayed as '.

Enter the dimensions format code.  Format codes less than 0 (i.e., with a
preceding `-') indicate that the units are feet and inches.  The first digit
represents the presentation mode `1' for feet/decimal feet, `2' for
feet/inches/decimal inches, or `3' for feet/inches/fractional inches.  The
second digit represents the number of digits appearing after the decimal point
(if any).  When working in metric units the default code is `13'.  When
working in feet the default code is `-30'.

The following table shows how an imperial dimension is displayed using the
various format codes:

         Format  Value
         Code    (in ft/inch)    Text

         -10     1' 7-"          2'
         -11     1' 7-"          1.6'
         -12     1' 7-"          1.64'
         -20     1' 7-"          1' 8"
         -21     1' 7-"          1' 7.7"
         -22     1' 7-"          1' 7.68"
         -23     1' 7-"          1' 7.683"
         -30     1' 7-"          1' 7-"

For all units, enter a value for solid tolerance.  The range, displayed in the
current unit, is 0.00001-0.1 meters.  This value sets the tolerance accuracy
for various calculations and represents the length of an entity line which
will be effective in the system operations.  Lengths shorter than this value
will be ignored, e.g., in operations like union, subtraction, hidden lines
removal, etc.  Unexpected results may occur if entities requiring fine
tolerances are included in files containing many large entities (requiring
larger tolerances) and vice versa.

Enter a value for the reference scale.  The range is 0.01-100000.  The
reference scale is the scale at which text and other scalable entities
(dimension text, linear patterns) will appear at their originally defined size
(real size = specified size x reference scale).  It is set in the \tscrn
command.  Initially the default in the geometric module is 1:100 and in the
Drawing Sheet Generator module (DSG) to 1:1.  (In the DSG it should not be
changed.)

Enter a size for arc segments.  The range is 0.0003-1 meters and is displayed
in the current unit.  Then enter the minimum and maximum number of segments in
an arc.  The range is 5-500.  (See \sarc).

If the grid is on, the current grid interval will be displayed on the input
line in the new unit.  Enter a new interval if required or press <ENTER> to
accept the current values.  Zero will turn the grid off.

NOTE: To change parameters individually, see \sarc, \grid, \ngrid, \adim,
\tscrn, \tol.
