**[Appendix B. Special Codes]{.underline}**

Exchange File Format

Version 3.3 (9/10/2004)

**[Special Codes]{.underline}**

Some fields have ranges defined by special codes. The following tables
define these codes.

**[Existence Flags]{.underline}**

Each data field has a corresponding existence flag. The following are
the positions for each existence flag:

Column 94: Existence flag for field 1

Column 96: Existence flag for field 2

Column 98: Existence flag for field 3

Column 100: Existence flag for field 4

Column 102: Existence flag for field 5

Column 104: Existence flag for field 6

Column 106: Existence flag for field 7

Column 108: Existence flag for field 8

Column 110: Existence flag for field 9

Column 112: Existence flag for field 10

The following are valid values for Existence Flags:

0 Known

1 Unknown

**[Obstruction Accuracy Codes]{.underline}**

Accuracy codes are 2 character codes which designate the accuracy of a
feature. The accuracy code is not the accuracy at which a feature is
collected but rather the minimum accuracy required for a feature
depending on where it falls within the OIS.

The first character of the accuracy code is the horizontal accuracy.

[Value]{.underline} [Accuracy]{.underline}

1 20 feet

2 50 feet

3 100 feet

The second character of the accuracy code is the vertical accuracy.

[Value]{.underline} [Accuracy]{.underline}

A 3 feet

B 10 feet

C 20 feet

D 50 feet

M ESTIMATED MAXIMUM ELEVATION\*

? NO TOP ELEVATION -- NO VERTICAL ACCURACY

The special accuracy code 99 indicates features that are not
obstructions (such as Geodetic Control, Photo Control, Polygons, etc.).
Refer to the "FAA No. 405" for minimum allowable accuracies for these
features.

A vertical accuracy designation of M, estimated maximum elevation, is
provided when the elevation of an object cannot be determined precisely,
as with mobile cranes.

**[Horizontal Datum Tie Codes]{.underline}**

\- UNDEFINED

B 5 CM GPS ANA

C 50 CM GPS ADAM

D 1:100,000 CLASSICAL 1ST ORDER

E 1:50,000 CLASSICAL 2ND ORDER CLASS I

F 1:20,000 CLASSICAL 2ND ORDER CLASS II

G 1:10,000 CLASSICAL 3RD ORDER CLASS I

H 1:5,000 CLASSICAL 3RD ORDER CLASS II

I 15 FT PHOTOGRAMMETRIC

J \> 15 FT OTHER

**[Ellipsoidal Datum Tie Codes]{.underline}**

\- UNDEFINED

B 15 CM GPS ANA

C 50 CM GPS ADAM

> D 1 M GEOID 96 MODEL (ORTHO+GEOID)

E \> 1 M OTHER

**[Orthometric Datum Tie Code]{.underline}**

\- UNDEFINED

A 1.0 MM \* SQRT(K) CLASSICAL 1ST ORDER CLASS I

B 1.4 MM \* SQRT(K) CLASSICAL 1ST ORDER CLASS II

C 2.0 MM \* SQRT(K) CLASSICAL 2ND ORDER CLASS I

D 2.6 MM \* SQRT(K) CLASSICAL 2ND ORDER CLASS II

E 4.0 MM \* SQRT(K) CLASSICAL 3RD ORDER

> F 24.0 MM \* SQRT(K) CLASSICAL AOC VERTICAL TIE

G 25 CM GPS ANA

H 10 FT PHOTOGRAMMETRIC

I \> 10 FT OTHER

**[Point Survey Status Attribute Code]{.underline}**

\- Undefined

D Not Verified

C Checked by Survey Methods

W New Point

I Checked by Visual Inspection

G Checked by General Inspection

R Retied

B New Base Elevation

T New Top Elevation

V New Vertical Position

? Questionable Position Change

P Photogrammetrically Determined Position

**[Control Type Attribute Code]{.underline}**

\- Undefined

> P PACS
>
> A SACS
>
> C TACS

T Triangulation Station

L Local Control

S Sub Point (Photo Control)

**[NAVAID Type Attribute Code]{.underline}**

Code Abbreviation Full Name

\- Undefined

\+ APBN Airport Beacon

= ALS Approach Lights

W ARSR Air Route Surveillance Radar

A ASR Airport Surveillance Radar

> , ATCBI ATCBI
>
> J BCM Back Course Marker

D DME Distance Measuring Equipment

Y FM Fan Marker

F GS Glide Slope

G IM Inner Marker

K LDA Localizer Type Directional Aid

> Z LFR Low Frequency Radio Range
>
> R LMM Locator Middle Marker

E LOC Localizer

S LOM Locator Outer Marker

> \> LRR Long Range Radar
>
> L MLSAZ MLS Azimuth Guidance

N MLSEL MLS Elevation Guidance

> V MLSDME DME associated with MLS
>
> H MM Middle Marker

X NDB Nondirectional Beacon

\# NDB/DME

B OTHER Other NAVAID

I OM Outer Marker

> & PAPI Precision Approach Path Indicator

\% PAR Precision Approach Radar

> ! PLASI PLASI
>
> \* PVASI Pulsating Visual Approach Slope Indicator
>
> \$ REIL Runway End Identifier Lights

O SDF Simplified Directional Facility

> : STARS STARS component
>
> M TACAN Tactical Air Navigation

C TDR GCA Touchdown Reflectors

( TRCV Tri-color Visual Approach Slope Indicator

> ) TVASI AT@-Visual Approach Slope Indicator
>
> \~ VASI Visual Approach Slope Indicator

P VOR VHF Omni Directional Range

T VOR/DME

Q VORTAC VOR + TACAN

**[Special Attribute Code]{.underline}**

\- Undefined

T Outside specified Obstruction Identification Surface (OIS)

Note: T refers to a feature which falls outside the surfaces defined in
the FAA NO. 405 but which is of interest.

**[Runway Approach Type Codes]{.underline}**

**Runway_Approach_Types: ANA surveys**

NUL NUL

PC1 ANA PC, Cat 1

PC2 ANA PC, Cat 2/3

AP1 ANA PC, Cat 1 Revision Date: January 28, 2004

AP2 ANA PC, Cat 2/3 Revision Date: January 28, 2004

**Runway Approach Types: CGR surveys**

NUL NUL

CGP PRECISION INSTRUMENT APPROACH, INCLUDES APPROACH AND PRIMARY
[]{.mark}SURFACES ONLY

CGD NONPRECISION APPROACH -- VISIBILITY MINIMUMS AS LOW AS ¾ MILE
INCLUDES APPROACH AND PRIMARY SURFACE ONLY

**Runway Approach Types: F77 surveys**

NUL NUL

PIR PRECISION INSTRUMENT APPROACH

ANP NONPRECISION APPROACH - UTILITY RUNWAY

C NONPRECISION APPROACH - VISIBILITY MINIMUMS GREATER THAN 3/4 MILE

D NONPRECISION APPROACH - VISIBILITY MINIMUMS AS LOW AS 3/4 MILE

AV VISUAL APPROACH - UTILITY RUNWAY

BV VISUAL APPROACH

BVC BV w/Supplemental C

**Runway Approach Types: OEP surveys**

NUL NUL

OEP Operation Evolution Plan

**Runway Approach Types: RBI surveys**

NUL NUL

RBI Ron Brown Airport Initiative

**[Poly Feature Survey Status Attribute Code]{.underline}**

\- Undefined

D Not Verified

C Checked by Survey Methods

W New Feature

I Checked by Visual Inspection

G Checked by General Inspection

R Retied

B New Base Elevation

T New Top Elevation

V New Vertical Position

? Questionable Position Change

P Photogrammetrically Determined Position

**[Source Codes]{.underline}**

F -- Field (ground survey: GPS or Classical)

E -- Manual Entry (direct numerical edits performed in the field)

R -- Remote Sensing (measurements made from interpreted imagery)

O -- Office (direct numerical edits performed in the office)