The STL format provides support for null values (see Section ).
A null value for a field in an STL table is indicated by inserting
the string `
<null>' at the appropriate place in the input file.
When CURSA reads this string it will interpret it as a null value.
Actually, if CURSA encounters any value for a field which it cannot
interpret given the data type of the column (such as a string containing
alphabetic characters in a field for an INTEGER column) then the field
is interpreted as null. However, when preparing STL files I recommend
that you indicate nulls using the string `
<null>'. This string
is recognised as indicating a null value even for CHARACTER columns.
When CURSA writes an STL catalogue null fields in the table are
represented by the string `
Null values are not permitted in the KAPPA variant of the STL format (see Appendix ).
CURSA Catalogue and Table Manipulation Applications