README.ANC

The files in the \ANCIL subdirectory are the volume descriptor,
leader, trailer, supplemental, and null volume files found on
Landsat tapes.

THE ANCILLARY FILES FROM THIS LANDSAT SCENE ARE IN A DIFFERENT
FORMAT FROM OTHER SCENES, AND MAY BE INCOMPLETE.  This scene was
retrieved from a copy of the original scene.  The copy contained
ancillary files of different sizes and lengths than the original.
THE NAMING CONVENTIONS FOR THE ANCILLARY FILES OF THIS SCENE
ARE SLIGHTLY DIFFERENT THAN THOSE OF OTHER LANDSAT TM SCENES.
Specifically, each quad has a Header File (H) for each band, and
has NO Volume Directory File (V), Trailer File (T), Supplemental 
Volume Directory File (P), P-Supplemental File (S), or Null Volume 
Directory File (N).

For this scene only, each band of data was preceded by an ancillary
file of record length 360 bytes. This file has been designated a 
"header" file (H) and appears to contain some of the information 
present in the normal Volume Directory file (V).  Following the 
"header" file is the Leader File (L), which seems to be the same 
as the normal leader file (see table below).  The next file contains 
the data, the first record of which is the Image File Descriptor (D), 
the same as on the normal TM scenes.  There are NO Trailer files (T), 
Supplemental Volume Files (P), P-supplemental files (S), or Null 
Volume Directory Files (N) available for this scene.

The following describes the naming convention for this scene:

Qntb
||||_ BAND NUMBER
|||__ FILE TYPE
||___ QUAD NUMBER
|____ Always Q


All ancillary file names are prefaced with Q.

QUAD NUMBER (n)

There are four possible quad numbers in a TM full scene (1-4). 
Within a TM full scene, the quads are arranged as follows:

                       _______________  
                      |       |       |
                      | QUAD1 | QUAD2 |
                      |_______|_______|
                      |       |       |
                      | QUAD3 | QUAD4 |
                      |_______|_______|


FILE TYPE (t)

The following file types are found on a TM tape:
                                            
The reference to "Section (S)/Table (T)" in the table below refers
to Section/Table numbers in the 1985 User's Guide for Landsat
Thematic Mapper Computer-Compatible Tapes.

                                      Record     Section (S)/
Code Description                      Length     Table (T)

V    Volume Directory File             360       S5.5
     Volume Descriptor Record                    S5.5.1/T5-4
     File Pointer Records                        S5.5.3/T5-5

L    Leader File                      4320       S5.5.3,S5.6.1
     Leader file Descriptor Record               S5.5.3/T5-7
     Scene Header Record                         S5.6.1.1/T5-13
     Map Projection Ancillary Record             S5.6.1.2/T5-15
     Radiometric Calibration
       Ancillary Record                          S5.6.1.3/T5-16

D    Image File Descriptor Record     4320       S5.5.3/T5-9

T    Trailer File                     4320       S5.5.3,S5.6.3
     Trailer File Descriptor Record              S5.5.3/T5-8
     Trailer Data Record                         S5.6.3/T5-19

P    Supplemental Volume Directory
       File                            360       S5.5/T5-4

S    P-Supplemental File                *        S5.7
     File Descriptor Record            540       T5-10
     Band Quality Records             3600       S5.7.1/T5-21
     Annotation Record                 540       S5.7.1/T5-20

N    Null Volume Directory File        360       S5.5
     Null Volume Descriptor Record               S5.5.1/T5-4

*Note that the P-Supplemental file has been saved as an
"unformatted" file such that it is 26280 bytes long with 1 "record"
of 540 bytes, 7 "records" of 3600 bytes, and 1 final "record" of
540 bytes.


BAND NUMBER (b)

Band numbers in a TM scene range from 1-7.  
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