Qualifying fields is adding one ore more constraints on some of the columns. The qualification syntax follows the ASU protocol:

• for character (char) columns: the qualification includes a comparison operator, like == for strict equality or ~ for caseless pattern matching, followed by a comparison value or a pattern
• for non-character columns: the qualification includes one or several comparison and logical operators and values.

Some typical examples:

keep only non-blank (i.e. specified, or not-null) values:	!=
restrict a number to the range 12.0 to 12.5:	12.0 .. 12.5
restrict a date to before June 1, 2000:	< 2000.06.01
restrict a stellar spectral type ((char) column) to early types:	=*[OBA]*

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Numeric fields

The following table describes all operators available on numeric fields (i.e. not flagged by (char)):

Operator	Meaning	Example
=	Strict equality (default)	=10
!=	Inequality	!=10
>=	Greater or equal	>=10
>	Strictly greater	>10
<=	Smaller or equal	<=10
<	Strictly smaller	<10
..	Range of numbers	5..10
+/-	Range defined by its mean and semi-amplitude (*)	8+/-2
&	AND (logical operator)	1..5 & 7..9
|	OR (logical operator)	1..5 | 7..9
,	List of values	0,1,2
<<;	List of values. Each value results in a separated table, in a way similar to the output from a list of targets. (**)	<<;1;2;3
!	NOT (logical operator)	! 1..5

(*) The +/- operator may alternatively be written ± if your keyboard allows this symbol. Note also that for DATE/TIME values, the semi-amplitude can only be given as a number representing decimal days, as e.g.   07-Apr-2001 12:00 ± 3.5    for the days 4 to 10 April 2001 (facility added in April 2001)
(**) since 23/06/2009

Values in Numeric fields

What follows the comparison operators are generally numbers; in a few cases, several ways of writing values are possible:

Type	Meaning	Example
null	Unspecified (blank)value	(<0)|null
now	Current date and time (DATE only)	< now
RA	Sexagesimal hours, minutes, seconds of time	23 56 .. 00 04
	Right ascension in decimal degrees	359 .. 001
DE	Sexagesimal degrees, minutes, seconds of arc	+41 45 .. +42 30
	Declination in decimal degrees	+41.75 .. +42.50
DATE/TIME	UT Date and time, alphabetic month	>= 1-Jan-1996
	UT Date and Time, numeric month	>= 1996.01.01 00:00:00
	Julian Date	>=JD2450083.5

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Character fields

The following table describes all operators available on character fields (i.e. flagged by (char)):

Operator	Meaning	Example
~	Caseless pattern matching (default)	~ngc*3532*
=	Pattern matching	=NGC*3532*
=~	Caseless equality	=~ngc
==	Strict equality	==NGC
~|	|-separated list of caseless pattern matchings	~|O*pec|WR*
=,	comma-separated list of alternatives	=,HST,IRAS
=|	|-separated list of alternatives	=|HST|IRAS
!=,	exclusion of a comma-separated list of alternatives	!=,HST,IRAS
!~	NOT caseless pattern matching	!~[obafgkm]*
!	NOT pattern matching	![OBAFGKM]*
!=	Strict inequality	!=NGC
>=	Alphabetically greater or equal	>=A
>	Alphabetically strictly greater	>M 51
<=	Alphabetically smaller or equal	<=B*
<	Alphabetically strictly smaller	< NGC
<<;	List of values separated by ;(*)	<<;val1;val2;val3

(*) (facilities added in June 2009)

Pattern matching symbols

What follows the pattern matching operators (~ = !~ !) is a pattern string which contains the following symbols:

Symbol	Meaning	Example
[...]	One of the characters defined within the brackets	=[OBA]*
	The - (dash or minus) indicates a range of characters	=[A-Za-z]*
[^...]	Any single character NOT contained within the brackets	=[^OBAFGMN]*
*	Replaces 0 to n characters	[OB]*
?	Replaces 1 character	A?C*

Note about Heading Blanks: when no operator is listed, the leading blanks (blanks at the left of a character column) are ignored.

last update: 13 Feb 2024