Columns

A column may contain either a single value for each row (as in standard relational database theory) or a one-dimensional array of values for each row. An array must be of fixed size, defined when the column is created. There is no upper limit to the number of elements which an array may contain. A single-valued column is called a scalar and a column containing an array is called a vector. The attributes of a column are listed in Table  and described below.

The attributes of an individual element of a vector column are somewhat different and are described in Section , below.

Table: Attributes of columns

Attribute	Name	Data	Mut-	Mand-	Default
		type	-able	-atory
Name	NAME	_CHAR		$\bullet$
Genus	GENUS	_INTEGER			physical: CAT__GPHYS
Expression	EXPR	_CHAR			` '
Data type	DTYPE	_INTEGER		$\bullet$
Character size	CSIZE	_INTEGER			20
Dimensionality	DIMS	_INTEGER			scalar: CAT__SCALR
Size§	SIZE	_INTEGER			1
Null or locum	NULL	_INTEGER			HDS: CAT__NULLD
Exception values	EXCEPT	_CHAR			` '
Scale factor	SCALEF	_DOUBLE			1.0D0
Zero point	ZEROP	_DOUBLE			0.0D0
Order	ORDER	_INTEGER			none: CAT__NOORD
Units	UNITS	_CHAR	$\bullet$		` '
External format	EXFMT	_CHAR	$\bullet$		varies with data type
Preferential display	PRFDSP	_LOGICAL	$\bullet$		true
Comments	COMM	_CHAR	$\bullet$		` '
Modification date	DATE	_DOUBLE	$\bullet$		0.0D0

The size of character strings; other data types have CSIZE = 0.

§

SIZE is a single-element array, not a scalar.