DXF file format: header variables

The HEADER section holds the drawing’s settings. Each variable is a 9 group carrying its name, such as $ACADVER, followed by one or more groups that carry its value; a point uses 10, 20 and (for 3D) 30. Only variables that are saved in the drawing appear. This page follows Autodesk’s AutoCAD 2014 DXF Reference, the newest edition published as a PDF. The AutoCAD 2018 online DXF Reference lists the same variables and adds one $ACADVER value, AC1032.

  0
SECTION
  2
HEADER
  9
$ACADVER
  1
AC1027
  9
$INSBASE
 10
0.0
 20
0.0
 30
0.0
  9
$INSUNITS
 70
4
  0
ENDSEC

A short HEADER section: an AutoCAD 2013 format drawing with its insertion base at the origin and millimetres as its units.

Values used by many variables

Kind	Values
Colour (62 or 70)	An AutoCAD Colour Index 1–255; 0 BYBLOCK; 256 BYLAYER; 257 BYENTITY where stated
Lineweight (370, and the DIMLWD/DIMLWE 70 values)	−3 Standard, −2 ByLayer, −1 ByBlock, 0–211 hundredths of a millimetre
Zero suppression (DIMZIN, DIMALTZ, DIMTZIN, DIMALTTZ)	0 suppresses zero feet and precisely zero inches; 1 includes zero feet and precisely zero inches; 2 includes zero feet and suppresses zero inches; 3 includes zero inches and suppresses zero feet
Orthographic view (UCSORTHOVIEW, PUCSORTHOVIEW)	0 not orthographic, 1 Top, 2 Bottom, 3 Front, 4 Back, 5 Left, 6 Right
“If nonzero” switches	Any nonzero value turns the setting on; 0 turns it off

Header variables

In the reference’s order (alphabetical). Points are in the world coordinate system unless the description says otherwise.

Variable	Code	Meaning
`$ACADMAINTVER`	70	Maintenance version number (should be ignored)
`$ACADVER`	1	Drawing database version: `AC1006` R10; `AC1009` R11 and R12; `AC1012` R13; `AC1014` R14; `AC1015` AutoCAD 2000; `AC1018` 2004; `AC1021` 2007; `AC1024` 2010; `AC1027` 2013; `AC1032` 2018 (2018 reference)
`$ANGBASE`	50	Direction of angle 0
`$ANGDIR`	70	1 clockwise angles; 0 counterclockwise
`$ATTMODE`	70	Attribute visibility: 0 none, 1 normal, 2 all
`$AUNITS`	70	Units format for angles
`$AUPREC`	70	Units precision for angles
`$CECOLOR`	62	Current entity colour: 0 BYBLOCK, 256 BYLAYER
`$CELTSCALE`	40	Current entity linetype scale
`$CELTYPE`	6	Entity linetype name, or BYBLOCK or BYLAYER
`$CELWEIGHT`	370	Lineweight of new objects
`$CEPSNID`	390	Plot style handle of new objects, used when $CEPSNTYPE is 3
`$CEPSNTYPE`	380	Plot style type of new objects: 0 by layer, 1 by block, 2 by dictionary default, 3 by object ID/handle
`$CHAMFERA`	40	First chamfer distance
`$CHAMFERB`	40	Second chamfer distance
`$CHAMFERC`	40	Chamfer length
`$CHAMFERD`	40	Chamfer angle
`$CLAYER`	8	Current layer name
`$CMLJUST`	70	Current multiline justification: 0 top, 1 middle, 2 bottom
`$CMLSCALE`	40	Current multiline scale
`$CMLSTYLE`	2	Current multiline style name
`$CSHADOW`	280	Shadow mode for a 3D object: 0 casts and receives shadows, 1 casts shadows, 2 receives shadows, 3 ignores shadows
`$DIMADEC`	70	Number of decimal places shown in angular dimensions
`$DIMALT`	70	Alternate unit dimensioning performed if nonzero
`$DIMALTD`	70	Alternate unit decimal places
`$DIMALTF`	40	Alternate unit scale factor
`$DIMALTRND`	40	Rounding of alternate units
`$DIMALTTD`	70	Decimal places of tolerance values in alternate units
`$DIMALTTZ`	70	Zero suppression for alternate tolerance values (0–3, above)
`$DIMALTU`	70	Units format for alternate units of every dimension type except angular: 1 scientific, 2 decimal, 3 engineering, 4 architectural (stacked), 5 fractional (stacked), 6 architectural, 7 fractional
`$DIMALTZ`	70	Zero suppression for alternate unit values (0–3, above)
`$DIMAPOST`	1	Alternate dimensioning suffix
`$DIMASO`	70	1 create associative dimensioning; 0 draw individual entities
`$DIMASSOC`	280	Associativity of dimensions: 0 exploded (lines, arcs, arrowheads and text drawn as separate objects); 1 non-associative single objects, whose value updates when a definition point moves; 2 associative, with definition points coupled to points on geometry
`$DIMASZ`	40	Dimension arrow size
`$DIMATFIT`	70	Placement when text and arrows do not both fit inside the extension lines: 0 both outside, 1 move arrows first then text, 2 move text first then arrows, 3 move whichever fits best. A leader is added to moved text when DIMTMOVE is 1
`$DIMAUNIT`	70	Angle format for angular dimensions: 0 decimal degrees, 1 degrees/minutes/seconds, 2 gradians, 3 radians, 4 surveyor’s units
`$DIMAZIN`	70	Zero suppression for angular dimensions: 0 show all leading and trailing zeros, 1 suppress leading zeros, 2 suppress trailing zeros, 3 suppress both
`$DIMBLK`	1	Arrow block name
`$DIMBLK1`	1	First arrow block name
`$DIMBLK2`	1	Second arrow block name
`$DIMCEN`	40	Size of centre mark or lines
`$DIMCLRD`	70	Dimension line colour (0 BYBLOCK, 256 BYLAYER)
`$DIMCLRE`	70	Extension line colour (0 BYBLOCK, 256 BYLAYER)
`$DIMCLRT`	70	Dimension text colour (0 BYBLOCK, 256 BYLAYER)
`$DIMDEC`	70	Decimal places for tolerance values of a primary units dimension
`$DIMDLE`	40	Dimension line extension
`$DIMDLI`	40	Dimension line increment
`$DIMDSEP`	70	Single-character decimal separator for decimal dimensions
`$DIMEXE`	40	Extension line extension
`$DIMEXO`	40	Extension line offset
`$DIMFAC`	40	Scale factor for the height of fraction and tolerance text: DIMTXT × DIMTFAC gives that height (listed under this name in the reference)
`$DIMGAP`	40	Dimension line gap
`$DIMJUST`	70	Horizontal text position: 0 above the dimension line, centred between extension lines; 1 above, next to the first extension line; 2 above, next to the second; 3 above and centred on the first extension line; 4 above and centred on the second
`$DIMLDRBLK`	1	Arrow block name for leaders
`$DIMLFAC`	40	Linear measurements scale factor
`$DIMLIM`	70	Dimension limits generated if nonzero
`$DIMLUNIT`	70	Units for every dimension type except angular: 1 scientific, 2 decimal, 3 engineering, 4 architectural, 5 fractional, 6 Windows desktop
`$DIMLWD`	70	Dimension line lineweight (−3, −2, −1 or 0–211, above)
`$DIMLWE`	70	Extension line lineweight (−3, −2, −1 or 0–211, above)
`$DIMPOST`	1	General dimensioning suffix
`$DIMRND`	40	Rounding value for dimension distances
`$DIMSAH`	70	Use separate arrow blocks if nonzero
`$DIMSCALE`	40	Overall dimensioning scale factor
`$DIMSD1`	70	Suppression of the first extension line: 0 not suppressed, 1 suppressed
`$DIMSD2`	70	Suppression of the second extension line: 0 not suppressed, 1 suppressed
`$DIMSE1`	70	First extension line suppressed if nonzero
`$DIMSE2`	70	Second extension line suppressed if nonzero
`$DIMSHO`	70	1 recompute dimensions while dragging; 0 drag the original image
`$DIMSOXD`	70	Suppress dimension lines outside the extension lines if nonzero
`$DIMSTYLE`	2	Dimension style name
`$DIMTAD`	70	Text above the dimension line if nonzero
`$DIMTDEC`	70	Number of decimal places shown for tolerance values
`$DIMTFAC`	40	Dimension tolerance display scale factor
`$DIMTIH`	70	Text inside extension lines horizontal if nonzero
`$DIMTIX`	70	Force text inside the extension lines if nonzero
`$DIMTM`	40	Minus tolerance
`$DIMTMOVE`	70	Text movement: 0 move the dimension line with the text, 1 add a leader when text is moved, 2 move text freely without a leader
`$DIMTOFL`	70	If text is outside the extension lines, force a line between them if nonzero
`$DIMTOH`	70	Text outside extension lines horizontal if nonzero
`$DIMTOL`	70	Dimension tolerances generated if nonzero
`$DIMTOLJ`	70	Vertical justification of tolerance values: 0 top, 1 middle, 2 bottom
`$DIMTP`	40	Plus tolerance
`$DIMTSZ`	40	Tick size; 0 means no ticks
`$DIMTVP`	40	Text vertical position
`$DIMTXSTY`	7	Dimension text style
`$DIMTXT`	40	Dimension text height
`$DIMTZIN`	70	Zero suppression for tolerance values (0–3, above)
`$DIMUPT`	70	Cursor for user-positioned text: 0 controls only the dimension line position, 1 controls the text position too
`$DIMZIN`	70	Zero suppression for primary unit values (0–3, above)
`$DISPSILH`	70	Silhouette curves of bodies in wireframe: 0 off, 1 on
`$DRAGVS`	349	Hard pointer to the visual style used while creating 3D solid primitives; default none
`$DWGCODEPAGE`	3	Drawing code page; set to the system code page when the drawing is created, not otherwise maintained
`$ELEVATION`	40	Current elevation set by ELEV
`$ENDCAPS`	280	Lineweight end caps for new objects: 0 none, 1 round, 2 angle, 3 square
`$EXTMAX`	10, 20, 30	Upper-right corner of the drawing extents
`$EXTMIN`	10, 20, 30	Lower-left corner of the drawing extents
`$EXTNAMES`	290	Symbol table naming: 0 Release 14 rules (up to 31 characters: A–Z, 0–9, `$`, `_`, `-`); 1 AutoCAD 2000 rules (up to 255 characters, including spaces and any characters not reserved by Windows or AutoCAD)
`$FILLETRAD`	40	Fillet radius
`$FILLMODE`	70	Fill mode on if nonzero
`$FINGERPRINTGUID`	2	Set when the drawing is created; identifies that drawing
`$HALOGAP`	280	Gap shown where an object is hidden by another, as a percentage of one unit, independent of zoom
`$HANDSEED`	5	Next available handle
`$HIDETEXT`	290	0 HIDE ignores text objects; 1 HIDE does not ignore them
`$HYPERLINKBASE`	1	Base path for relative hyperlinks; if empty the drawing’s path is used
`$INDEXCTL`	280	Indexes saved in the drawing: 0 none, 1 layer index, 2 spatial index, 3 both
`$INSBASE`	10, 20, 30	Insertion base set by BASE
`$INSUNITS`	70	Default drawing units for DesignCenter blocks: 0 unitless, 1 inches, 2 feet, 3 miles, 4 millimetres, 5 centimetres, 6 metres, 7 kilometres, 8 microinches, 9 mils, 10 yards, 11 ångströms, 12 nanometres, 13 microns, 14 decimetres, 15 decametres, 16 hectometres, 17 gigametres, 18 astronomical units, 19 light years, 20 parsecs
`$INTERFERECOLOR`	62	Colour index of interference objects made by INTERFERE; default 1
`$INTERFEREOBJVS`	345	Hard pointer to the visual style for interference objects; default Conceptual
`$INTERFEREVPVS`	346	Hard pointer to the viewport visual style during interference checking; default 3d Wireframe
`$INTERSECTIONCOLOR`	70	Colour of intersection polylines: 1–255 colour index, 0 BYBLOCK, 256 BYLAYER, 257 BYENTITY
`$INTERSECTIONDISPLAY`	290	Intersection polylines: 0 not shown, 1 shown
`$JOINSTYLE`	280	Lineweight joints for new objects: 0 none, 1 round, 2 angle, 3 flat
`$LIMCHECK`	70	Limits checking on if nonzero
`$LIMMAX`	10, 20	Upper-right corner of the drawing limits
`$LIMMIN`	10, 20	Lower-left corner of the drawing limits
`$LTSCALE`	40	Global linetype scale
`$LUNITS`	70	Units format for coordinates and distances
`$LUPREC`	70	Units precision for coordinates and distances
`$LWDISPLAY`	290	Lineweights on the Model or Layout tab: 0 not shown, 1 shown
`$MAXACTVP`	70	Maximum number of viewports regenerated
`$MEASUREMENT`	70	Drawing units: 0 English, 1 metric
`$MENU`	1	Name of the menu file
`$MIRRTEXT`	70	Mirror text if nonzero
`$OBSCOLOR`	70	Colour of obscured lines (hidden lines shown by HIDE or SHADEMODE), used only when $OBSLTYPE is not 0: 0 and 256 entity colour, 1–255 a colour index
`$OBSLTYPE`	280	Linetype of obscured lines, independent of zoom: 0 off (default), 1 solid, 2 dashed, 3 dotted, 4 short dash, 5 medium dash, 6 long dash, 7 double short dash, 8 double medium dash, 9 double long dash, 10 medium long dash, 11 sparse dot
`$ORTHOMODE`	70	Ortho mode on if nonzero
`$PDMODE`	70	Point display mode
`$PDSIZE`	40	Point display size
`$PELEVATION`	40	Current paper space elevation
`$PEXTMAX`	10, 20, 30	Maximum extents of paper space
`$PEXTMIN`	10, 20, 30	Minimum extents of paper space
`$PINSBASE`	10, 20, 30	Paper space insertion base point
`$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
`$PLINEGEN`	70	Linetype around 2D polyline vertices: 1 continuous pattern around vertices; 0 each segment starts and ends with a dash
`$PLINEWID`	40	Default polyline width
`$PROJECTNAME`	1	Project name, used to find external references and images not found on their original path
`$PROXYGRAPHICS`	70	Whether images of proxy objects are saved
`$PSLTSCALE`	70	Paper space linetype scaling: 1 no special scaling; 0 viewport scaling governs linetype scaling
`$PSTYLEMODE`	290	Plot style mode: 0 named plot style tables; 1 colour-dependent plot style tables
`$PSVPSCALE`	40	View scale for new viewports: 0 scaled to fit; greater than 0 a scale factor
`$PUCSBASE`	2	Name of the UCS defining the origin and orientation of orthographic UCS settings (paper space)
`$PUCSNAME`	2	Current paper space UCS name
`$PUCSORG`	10, 20, 30	Current paper space UCS origin
`$PUCSORGBACK`	10, 20, 30	New UCS origin after setting the paper space UCS to BACK while PUCSBASE is WORLD
`$PUCSORGBOTTOM`	10, 20, 30	The same for BOTTOM
`$PUCSORGFRONT`	10, 20, 30	The same for FRONT
`$PUCSORGLEFT`	10, 20, 30	The same for LEFT
`$PUCSORGRIGHT`	10, 20, 30	The same for RIGHT
`$PUCSORGTOP`	10, 20, 30	The same for TOP
`$PUCSORTHOREF`	2	When the paper space UCS is orthographic, the UCS it is relative to; empty means WORLD
`$PUCSORTHOVIEW`	70	Orthographic type of the paper space UCS (0–6, above)
`$PUCSXDIR`	10, 20, 30	Current paper space UCS X axis
`$PUCSYDIR`	10, 20, 30	Current paper space UCS Y axis
`$QTEXTMODE`	70	Quick text mode on if nonzero
`$REGENMODE`	70	REGENAUTO on if nonzero
`$SHADEDGE`	70	0 faces shaded, edges not highlighted; 1 faces shaded, edges black; 2 faces not filled, edges in entity colour; 3 faces in entity colour, edges black
`$SHADEDIF`	70	Percentage of ambient to diffuse light, 1–100, default 70
`$SHADOWPLANELOCATION`	40	Z of the ground shadow plane
`$SKETCHINC`	40	Sketch record increment
`$SKPOLY`	70	0 sketch lines; 1 sketch polylines
`$SORTENTS`	280	Object sorting, bit flags: 0 off; 1 for object selection, 2 object snap, 4 redraws, 8 MSLIDE slides, 16 REGEN, 32 plotting, 64 PostScript output
`$SPLINESEGS`	70	Line segments per spline patch
`$SPLINETYPE`	70	Spline curve type for PEDIT Spline
`$SURFTAB1`	70	Mesh tabulations in the first direction
`$SURFTAB2`	70	Mesh tabulations in the second direction
`$SURFTYPE`	70	Surface type for PEDIT Smooth
`$SURFU`	70	Surface density in M for PEDIT Smooth
`$SURFV`	70	Surface density in N for PEDIT Smooth
`$TDCREATE`	40	Local date and time the drawing was created (see dates)
`$TDINDWG`	40	Total editing time
`$TDUCREATE`	40	Universal date and time the drawing was created
`$TDUPDATE`	40	Local date and time of the last update
`$TDUSRTIMER`	40	User elapsed timer
`$TDUUPDATE`	40	Universal date and time of the last update or save
`$TEXTSIZE`	40	Default text height
`$TEXTSTYLE`	7	Current text style name
`$THICKNESS`	40	Current thickness set by ELEV
`$TILEMODE`	70	1 for previous release compatibility mode; 0 otherwise
`$TRACEWID`	40	Default trace width
`$TREEDEPTH`	70	Maximum depth of the spatial index
`$UCSBASE`	2	Name of the UCS defining the origin and orientation of orthographic UCS settings
`$UCSNAME`	2	Name of the current UCS
`$UCSORG`	10, 20, 30	Origin of the current UCS
`$UCSORGBACK`	10, 20, 30	New UCS origin after setting the model space UCS to BACK while UCSBASE is WORLD
`$UCSORGBOTTOM`	10, 20, 30	The same for BOTTOM
`$UCSORGFRONT`	10, 20, 30	The same for FRONT
`$UCSORGLEFT`	10, 20, 30	The same for LEFT
`$UCSORGRIGHT`	10, 20, 30	The same for RIGHT
`$UCSORGTOP`	10, 20, 30	The same for TOP
`$UCSORTHOREF`	2	When the model space UCS is orthographic, the UCS it is relative to; empty means WORLD
`$UCSORTHOVIEW`	70	Orthographic type of the model space UCS (0–6, above)
`$UCSXDIR`	10, 20, 30	Direction of the current UCS X axis
`$UCSYDIR`	10, 20, 30	Direction of the current UCS Y axis
`$UNITMODE`	70	Low bit set: show fractions, feet-and-inches and surveyor’s angles in input format
`$USERI1` – `$USERI5`	70	Five integers for third-party developers
`$USERR1` – `$USERR5`	40	Five reals for third-party developers
`$USRTIMER`	70	0 timer off; 1 timer on
`$VERSIONGUID`	2	Identifies this version of the drawing; changes when the drawing is modified
`$VISRETAIN`	70	0 do not keep xref-dependent visibility settings; 1 keep them
`$WORLDVIEW`	70	0 do not change the UCS; 1 set the UCS to the WCS during DVIEW and VPOINT
`$XCLIPFRAME`	290	Xref clipping boundary: 0 not visible, 1 visible
`$XEDIT`	290	In-place reference editing of this drawing from another: 0 not allowed, 1 allowed

Revised VPORT variables

These variables predate Release 11, which gave each viewport its own settings. They are still read from DXF files, but when a VPORT table with *ACTIVE entries is present (as in any file written by Release 11 or later), the table’s values override them.

Variable	Code	Meaning
`$FASTZOOM`	70	Fast zoom enabled if nonzero
`$GRIDMODE`	70	Grid on if nonzero
`$GRIDUNIT`	10, 20	Grid X and Y spacing
`$SNAPANG`	50	Snap grid rotation angle
`$SNAPBASE`	10, 20	Snap and grid base point (in the UCS)
`$SNAPISOPAIR`	70	Isometric plane: 0 left, 1 top, 2 right
`$SNAPMODE`	70	Snap on if nonzero
`$SNAPSTYLE`	70	Snap style: 0 standard, 1 isometric
`$SNAPUNIT`	10, 20	Snap X and Y spacing
`$VIEWCTR`	10, 20	X and Y of the centre of the current view
`$VIEWDIR`	10, 20, 30	Viewing direction (from the target, in the WCS)
`$VIEWSIZE`	40	Height of the view

Dates and times

$TDCREATE, $TDUCREATE, $TDUPDATE and $TDUUPDATE are Julian dates: the whole part is the Julian day number and the fraction is the fraction of a day. 31 December 1999 at 21:58:35 GMT is 2451544.91568287. Seconds since midnight are 86400 × (value − whole part). The local times are true Julian dates only when the computer’s clock is set to UTC.

$TDINDWG and $TDUSRTIMER are elapsed times in the same form: number of days, then the fraction of a day.

The reference also describes the CDATE system variable, which is not saved in the file: a real number YYYYMMDD.HHMMSShsec (hsec in hundredths), such as 20051231.21583575 for 31 December 2005 at 21:58:35.75. CDATE values sort correctly but cannot be subtracted.

Sources

AutoCAD 2014 DXF Reference – Autodesk, March 2013, chapter 2 (HEADER section)
AutoCAD 2018 DXF Reference: HEADER section group codes – Autodesk’s online edition, which adds AC1032

.DXF File Format – Header variables

Values used by many variables

Header variables

Revised VPORT variables

Dates and times

Sources