Temporal network point values must satisfy the constraints specified in the section called “Validity of Temporal Types” so that they are well defined. An error is raised whenever one of these constraints are not satisfied. Examples of incorrect values are as follows.

-- Null values are not allowed
SELECT tnpoint 'NULL@2001-01-01 08:05:00';
SELECT tnpoint 'Point(0 0)@NULL';
-- Base type is not a network point
SELECT tnpoint 'Point(0 0)@2001-01-01 08:05:00';
-- Multiple routes in a continuous sequence
SELECT tnpoint '[Npoint(1, 0.2)@2001-01-01 09:00:00, Npoint(2, 0.2)@2001-01-01 09:05:00)';

We present next the operation for temporal network point types. Most functions for temporal types described in the previous chapters can be applied for temporal network point types. Therefore, in the signatures of the functions, the notation base also represents an npoint and the notations ttype, tpoint, and tgeompoint also represent a tnpoint. Furthermore, the functions that have an argument of type geometry accept in addition an argument of type npoint. To avoid redundancy, we only present next some examples of these functions and operators for temporal network points.