[Proj] Custom nadgrid and .lla format again

[Michal Seidl]

Hellow,
I would like to confirm my suspecting that there is a little mistake in
README.GRD file which describes *.lla format. As I can see values in lla
files distributed with proj it seems to me it is something like this

<line_no>: <x_shift> <y_shift> <dx_shift> <dy_shift> *

So there is line number, x and y shift, and then there are only differences 
following.

I just guess from values. Second and next pair values are much smaller than
first pair of values.
There can be also problem in units. Are difference in micro (milionth)
seconds of arc? diff= diff(deg)*3600E6?


Here is what is documented
=========
.....

Subsequent lines are:

<line_no>: <x_shift> <y_shift> *

The <line_no> is zero based, and will vary from 0 to <grid_size_y>-1.  The 
number of x/y shift pairs will match <grid_size_x>.  Grid lines can be
split over multiple physical text lines.  Use the colon to identify starts
of new grid lines.  The shift values are in millionths of a secondc of arc. 


For example, from MD.lla:

Maryland - HP
  25  17   1   -80.00000      .25000    37.00000      .25000
0: 5107 -2502 -700 496 -656 468 -587 418 -481 347 -325 256 -111 152 166 50
493 -37 854 -96 1221 -118 1568 -125 1953 -143 2433 -195 2464 -281 2529 -395
1987 -729 447 -916 -3011 -1181 -5559 -406 -6094 541 -5714 1110 -5247 1289
-4993 1254 -4960 1151
1: 4757 -1695 -644 429 -627 411 -602 368 -555 299 -470 206 -328 96 -125 -15

=============

Thanks for your reply, Michal



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