.de BR
.in 0
.in +8n
.ti -3n
..

.Th XLIM
.S2 SUMMARY:
Set time axis limits for trace plot

XLIM [ON|OFF] [ ref offset | GMT beg | CAL beg | VEL vref voffsetb  ] [ ref offset | GMT end | CAL end | VEL vref voffsete ]


.S2 INPUT:
ON               : Turn on plot limits returning to previous value
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OFF              : Turn off plot limits
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ref              : A header reference value for the cut which is one of B|E|O|A|Tn where n=0,...,9
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offset           : Number of seconds relative to the reference value.  refbeg offset refers to the start point refend offset refers to the  end  point
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CAL              : Calendar time in YEAR MONTH DAY HOUR MINUTE SECOND MILLISECOND
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GMT              : GMT time in YEAR DAYOFYEAR HOUR MINUTE SECOND MILLISECOND
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VEL      : If O and DIST are set, select a time window about the group velocity vref. Internally input is adjusted so that the tiem window exists

.S2 DESCRIPTION:
This permits user modification of the trace display in PLOT1 and PLOTPK.
One must be careful about the window because PLOT1 or PLOTPK can have either
ABSOLUTE or RELATIVE plot modes. 
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In the ABSOLUTE display mode, origin time is one marker that could be
In the RELATIVE mode, trace alignment is permitted. For example, to look
at all marked P-wave first arrivals in relative time, one may try a
.nf
	xlim A -10 A 10
	plot1 RELATIVE
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Note that if the ABSOLUTE plot mode had been used, then the display would
have the P arrivals in absolute time and they would not be aligned.
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Note that some combinations, such as xlim A -10 T0 +20, will not have the desired outcome with traces at different distances since the windows are different for each distance. The program will use the common window.
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The option for CAL or GMT timesd was introduced 11 JAN 2005 to permit selection
of time windows from very long time segments. The following are equivalent:
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   XLIM GMT 2005 001 01 02 03 456 GMT 2005 032 06 05 04 321
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   XLIM GMT 2005 001 01 02 03 456 CAL 2005 02 01 06 05 04 321
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   XLIM CAL 2005 01 01 01 02 03 456 GMT 2005 032 06 05 04 321
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   XLIM CAL 2005 01 01 01 02 03 456 CAL 2005 02 01 06 05 04 321
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which cuts from January 1, 2005 01:02:03.456 to February 1, 2006 06:05:04.321
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The velocity cut was introduced to look at a set of interstation Green's functions and also to
focus on a surface-wave arrival for moment tensor inversion. Some examples are
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VEL 3.3 -30 VEL 3.3 70
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which gives a window 100 seconds long starting 30 seconds before the arrival with a group velocity of 3.3 km/s

.S2 "SAC COMPATIBILITY:"
.S2 "Note:"
The VEL limit will only work in the relative mode. In addition if the start time is before the first sample, the velocity display is not permitted.  This is related to the difficulty of pre-padding with zeros.
.S2 "SEE ALSO":
CUT, PLOT1, PLOTPK

