| $pelevation    | 40     | current paper space elevation       |
|----------------|--------|-------------------------------------|
| $pextmax       | 10, 20,| maximum x, y, and z extents for     |
|                | 30     | paper space                         |
|----------------|--------|-------------------------------------|
| $pextmin       | 10, 20,| minimum x, y, and z extents for     |
|                | 30     | paper space                         |
|----------------|--------|-------------------------------------|
| $plimcheck     | 70     | limits checking in paper space      |
|                |        | when nonzero                        |
|----------------|--------|-------------------------------------|
| $plimmax       | 10, 20 | maximum x and y limits in paper     |
|                |        | space                               |
|----------------|--------|-------------------------------------|
| $plimmin       | 10, 20 | minimum x and y limits in paper     |
|                |        | space                               |
|----------------|--------|-------------------------------------|
| $plinegen      | 70     | governs the generation of linetype  |
|                |        | patterns around the vertices        |
|                |        | of a 2d polyline                    |
|                |        | 1 = linetype is generated in        |
|                |        | a continuous pattern around         |
|                |        | vertices of the polyline            |
|                |        | 0 = each segment of the polyline    |
|                |        | starts and ends with a dash         |
|----------------|--------|-------------------------------------|
| $plinewid      | 40     | default polyline width              |
|----------------|--------|-------------------------------------|
| $psltscale     | 70     | controls paper space linetype       |
|                |        | scaling                             |
|                |        | 1 = no special linetype scaling     |
|                |        | 0 = viewport scaling governs        |
|                |        | linetype scaling                    |
|----------------|--------|-------------------------------------|
| $pucsname      | 2      | current paper space ucs name        |
|----------------|--------|-------------------------------------|
| $pucsorg       | 10, 20,| current paper space ucs origin      |
|                | 30     |                                     |
|----------------|--------|-------------------------------------|
| $pucsxdir      | 10, 20,| current paper space ucs x axis      |
|                | 30     |                                     |
|----------------|--------|-------------------------------------|
| $pucsydir      | 10, 20,| current paper space ucs y axis      |
|                | 30     |                                     |
|----------------|--------|-------------------------------------|
| $qtextmode     | 70     | quick text mode on if nonzero       |
|----------------|--------|-------------------------------------|
| $regenmode     | 70     | regenauto mode on if nonzero        |
|----------------|--------|-------------------------------------|
| $shadedge      | 70     | 0 = faces shaded, edges not         |
|                |        | highlighted                         |
|                |        | 1 = faces shaded, edges highlighted |
|                |        | in black                            |
|                |        | 2 = faces not filled, edges in      |
|                |        | entity color                        |
|                |        | 3 = faces in entity color,          |
|                |        | edges in black                      |
|----------------|--------|-------------------------------------|
| $shadedif      | 70     | percent ambient/diffuse light,      |
|                |        | range 1-100, default 70             |
|----------------|--------|-------------------------------------|
| $sketchinc     | 40     | sketch record increment             |
| $skpoly        | 70     | 0 = sketch lines, 1 = sketch        |
|                |        | polylines                           |
|----------------|--------|-------------------------------------|
| $splframe      | 70     | spline control polygon display,     |
|                |        | 1 = on, 0 = off                     |
|----------------|--------|-------------------------------------|
| $splinesegs    | 70     | number of line segments per spline  |
|                |        | patch                               |
|----------------|--------|-------------------------------------|
| $splinetype    | 70     | spline curve type for pedit spline  |
|                |        | (see your autocad reference manual) |
|----------------|--------|-------------------------------------|
| $surftab1      | 70     | number of mesh tabulations in first |
|                |        | direction                           |
|----------------|--------|-------------------------------------|
| $surftab2      | 70     | number of mesh tabulations in       |
|                |        | second direction                    |
|----------------|--------|-------------------------------------|
| $surftype      | 70     | surface type for pedit smooth       |
|                |        | (see your autocad reference manual) |
|----------------|--------|-------------------------------------|
| $surfu         | 70     | surface density (for pedit smooth)  |
|                |        | in m direction                      |
|----------------|--------|-------------------------------------|
| $surfv         | 70     | surface density (for pedit smooth)  |
|                |        | in n direction                      |
|----------------|--------|-------------------------------------|
| $tdcreate      | 40     | date/time of drawing creation       |
|----------------|--------|-------------------------------------|
| $tdindwg       | 40     | cumulative editing time for         |
|                |        | this drawing                        |
|----------------|--------|-------------------------------------|
| $tdupdate      | 40     | date/time of last drawing update    |
|----------------|--------|-------------------------------------|
| $tdusrtimer    | 40     | user elapsed timer                  |
|----------------|--------|-------------------------------------|
| $textsize      | 40     | default text height                 |
|----------------|--------|-------------------------------------|
| $textstyle     | 7      | current text style name             |
|----------------|--------|-------------------------------------|
| $thickness     | 40     | current thickness set by elev       |
|                |        | command                             |
|----------------|--------|-------------------------------------|
| $tilemode      | 70     | 1 for previous release              |
|                |        | compatibility mode, 0 otherwise     |
|----------------|--------|-------------------------------------|
| $tracewid      | 40     | default trace width                 |
|----------------|--------|-------------------------------------|
| $ucsname       | 2      | name of current ucs                 |
|----------------|--------|-------------------------------------|
| $ucsorg        | 10, 20,| origin of current ucs (in wcs)      |
|                | 30     |                                     |
|----------------|--------|-------------------------------------|
| $ucsxdir       | 10, 20,| direction of current ucs's x axis   |
|                | 30     | (in world coordinates)              |
|----------------|--------|-------------------------------------|
| $ucsydir       | 10, 20,| direction of current ucs's y axis   |
|                | 30     | (in world coordinates)              |
|----------------|--------|-------------------------------------|
| $unitmode      | 70     | low bit set = display fractions,    |
|                |        | feet-and-inches, and surveyor's     |
|                |        | angles in input format              |
|----------------|--------|-------------------------------------|
| $useri1 - 5    | 70     | five integer variables intended     |
|                |        | for use by third-party developers   |
|----------------|--------|-------------------------------------|
| $userr1 - 5    | 40     | five real variables intended        |
|                |        | for use by third-party developers   |
|----------------|--------|-------------------------------------|
| $usrtimer      | 70     | 0 = timer off, 1 = timer on         |
|----------------|--------|-------------------------------------|
| $visretain     | 70     | 0 = don't retain xref-dependent     |
|                |        | visibility settings, 1 = retain     |
|                |        | xref-dependent visibility settings  |
|----------------|--------|-------------------------------------|
| $worldview     | 70     | 1 = set ucs to wcs during           |
|                |        | dview/vpoint, 0 = don't change ucs  |
+---------------------------------------------------------------+</pre>
    <pre>the following header variables existed prior to autocad release 11 
but now have independent settings for each active viewport. dxfin 
honors these variables when read from dxf files, but if a vport 
symbol table with *active entries is present (as is true for any dxf 
file produced by release 11 or higher), the values in the vport 
table entries override the values of these header variables.</pre>
    <pre>table 11-4. revised vport header variables
+===============================================================+
| variable       | type   | description                         |
|----------------|--------|-------------------------------------|
| $fastzoom      | 70     | fast zoom enabled if nonzero        |
|----------------|--------|-------------------------------------|
| $gridmode      | 70     | grid mode on if nonzero             |
|----------------|--------|-------------------------------------|
| $gridunit      | 10, 20 | grid x and y spacing                |
|----------------|--------|-------------------------------------|
| $snapang       | 50     | snap grid rotation angle            |
|----------------|--------|-------------------------------------|
| $snapbase      | 10, 20 | snap/grid base point (in ucs)       |
|----------------|--------|-------------------------------------|
| $snapisopair   | 70     | isometric plane: 0 = left, 1 = top, |
|                |        | 2 = right                           |
|----------------|--------|-------------------------------------|
| $snapmode      | 70     | snap mode on if nonzero             |
|----------------|--------|-------------------------------------|
| $snapstyle     | 70     | snap style: 0 = standard,           |
|                |        | 1 = isometric                       |
|----------------|--------|-------------------------------------|
| $snapunit      | 10, 20 |snap grid x and y spacing            |
|----------------|--------|-------------------------------------|
| $viewctr       | 10, 20 |xy center of current view on screen  |
|----------------|--------|-------------------------------------|
| $viewdir       | 10, 20,| viewing direction (direction from   |
|                | 30     | target, in wcs)                     |
|----------------|--------|-------------------------------------|
| $viewsize      | 40     | height of view                      |
+----------------|--------|-------------------------------------+</pre>
    <pre>the date/time variables ($tdcreate and $tdupdate) are output as real 
numbers in the following format:</pre>
    <pre>   &lt;julian date&gt;.&lt;fraction&gt;</pre>
    <pre>the elapsed time variables ($tdindwg and $tdusrtimer) have a similar 
format:</pre>
    <pre>   &lt;number of days&gt;.&lt;fraction&gt;</pre>
    <pre>the date and time variables are described on page 299.
</pre>
    <pre>tables section
--------------
the tables section contains several tables, each of which contains a 
variable number of table entries.</pre>
    <pre>the order of the tables may change, but the ltype table will always 
precede the layer table. each table is introduced with a 0 group 
with the label table. this is followed by a 2 group identifying the 
particular table (vport, ltype, layer, style, view, dimstyle, ucs or 
appid) and a 70 group that specifies the maximum number of table 
entries that may follow. table names are always output in uppercase 
characters.</pre>
    <pre>the tables in a drawing can contain deleted items, but these are not 
written to the dxf file. thus, fewer table entries may follow the 
table header than are indicated by the 70 group, so don't use the 
count in the 70 group as an index to read in the table. this group 
is provided so that a program which reads dxf files can allocate an 
array large enough to hold all the table entries that follow.</pre>
    <pre>following this header for each table are the table entries. each 
table item consists of a 0 group identifying the item type (same as 
table name, e.g., ltype or layer), a 2 group giving the name of the 
table entry, a 70 group specifying flags relevant to the table entry 
(defined for each following table), and additional groups that give 
the value of the table entry. the end of each table is indicated by 
a 0 group with the value endtab.</pre>
    <pre>the 70 group flag bit values that apply to all table entries are 
described in the following chart. additional 70 group values that 
apply to layer, style, and view table entries are described in the 
appropriate sections below.</pre>
    <pre>table 11-5. group 70 bit codes that apply to all table entries
+===============================================================+
| flag bit | meaning                                            |
| value    |                                                    |