Nursing Variables and Constant Values

From the ancient days of BBC BASIC I am today still trying to pick up some PHP to help me grasp Drupal (and Ruby).

In declaring variables - a key element of computer programs - I thought about the following both as a VARIABLE -

$nursing_care = "variable"

- and as a CONSTANT.

Which made me wonder: when do we want nursing to be a 'variable' and when a 'constant'?

The answer is of course obvious.

Nursing care must be a VARIABLE when it reflects the care plans and objectives that relate to a person - a unique individual.

Alternately, what must be declared as CONSTANT are -

safety, values and good-high quality nursing care.

You may wish to consider what other aspects of nursing and your practice are either variable or constant in nature?