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For some keywords it makes sense to do a selection on a range of values, and the command interpreter accepts interval and relational specifications:
SEL RA = (6:10:30 to 18:05:) : find all objects in this RA interval
SEL DEC = (0:: to 70::) : find all objects between 0 and 70 degrees declination.
SEL DEC > 20:: : find all objects above 20 degrees decl.
SEL DATE >= 3MAR87 : all observation on or after 3 March 1987
The last examples show that operators such as > , >= , < , <= , = and <> (not equal) can be used. Furthermore, the syntax interpeter understands logical constructions such as:
SEL RA = (6:: to 18::) & DEC = (0::, to 70::) & EXPO > 800
SEL (OBJECT = N*4151 & DATE <= 3MAR89) | OBJECT = M81*
Here, the & stands for the logical AND operator; the | symbol represents the logical OR operator. For these operators one may also use the Fortran operators .AND. and .OR. , and similarly .GT., .GE., .LT., .LE., .EQ. and .NE..