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author | rsc <devnull@localhost> | 2005-01-03 06:40:20 +0000 |
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committer | rsc <devnull@localhost> | 2005-01-03 06:40:20 +0000 |
commit | 058b0118a52061ad57694c01fc8763b22b789c4d (patch) | |
tree | 6685f04dea5ed68edaa34998c976aed34c55fe94 /man/man7/map.7 | |
parent | 2600337aa704efbeba8201e88147a764b4fd2b90 (diff) | |
download | plan9port-058b0118a52061ad57694c01fc8763b22b789c4d.tar.gz plan9port-058b0118a52061ad57694c01fc8763b22b789c4d.tar.bz2 plan9port-058b0118a52061ad57694c01fc8763b22b789c4d.zip |
Some man pages.
Diffstat (limited to 'man/man7/map.7')
-rw-r--r-- | man/man7/map.7 | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/man/man7/map.7 b/man/man7/map.7 new file mode 100644 index 00000000..80e1eebf --- /dev/null +++ b/man/man7/map.7 @@ -0,0 +1,87 @@ +.TH MAP 7 +.SH NAME +map \- digitized map formats +.SH DESCRIPTION +Files used by +.IR map (7) +are a sequence of structures of the form: +.PP +.EX +struct { + signed char patchlatitude; + signed char patchlongitude; + short n; + union { + struct { + short latitude; + short longitude; + } point[n]; + struct { + short latitude; + short longitude; + struct { + signed char latdiff; + signed char londiff; + } point[\-n]; + } highres; + } segment; +}; +.EE +where +.B short +stands for 16-bit integers and there is no padding within or between +.BR structs . +Shorts are stored in little-endian order, low byte first. +To assure portability, +.I map +accesses them bytewise. +.PP +Fields +.L patchlatitude +and +.L patchlongitude +tell to what +10-degree by 10-degree +patch of the earth's surface a segment belongs. +Their values range from \-9 to 8 and from \-18 to 17, +respectively, and indicate the coordinates of the +southeast corner of the patch in units of 10 degrees. +.PP +Each segment of +.RB | n | +points is connected; consecutive segments +are not necessarily related. +Latitude and longitude +are measured in units of 0.0001 radian. +If +.B n +is negative, then +differences to the first and succeeding points +are measured in units of 0.00001 radian. +Latitude is counted positive to the north and +longitude positive to the west. +.PP +The patches are ordered lexicographically by +.L patchlatitude +then +.LR patchlongitude . +A printable +index to the first segment of each patch +in a file named +.I data +is kept in an associated file named +.IB data .x\f1. +Each line of an index file contains +.L patchlatitude, +.L patchlongitude +and the byte position +of the patch +in the map file. +Both the map file and the index file are ordered by +patch latitude and longitude. +.SH "SEE ALSO" +.IR map (7) +.br +The data comes from the World Data Bank I and II and +U.S. Government sources: the Census Bureau, Geological +Survey, and CIA. |