external.format

describes data that has been 'externally converted' using one of the 'conversion' or 'processing' codes provided with Pick. As a general rule, 'external format' means data is in a 'human-readable' format.

The main advantage of an 'internal' format is that it takes much less time to compare two values.

For instance, time values are not stored as the human readable form. Rather, they are converted using the 'mt' input processing code, which takes a legal 'external' time such as '14:00' (2:00 p.m.) and calculates the number of seconds past midnight for this value, which would be the 'internal' value. In this case, the 'internal' form would be '50400'. The same 'mt' code used as an output processing code may be used to convert the internal value to its 'external' form.

Dates are also more easily manipulated if stored in an 'internal' format. A input processing code of 'd' will take an external date, use a calculation to determine the number of days that have elapsed since December 31st, 1967 (day 0 (zero) on the Pick calendar), and store an 'internal' julian date. A similar output processing code will convert an 'internal' date to its human-readable 'external' form. See the date processing codes for the various output formats available.

In addition, numerical values are more easily handled by the system if they are all stored as integer amounts, and the decimal point (if any) is inserted only upon output. Typical American dollar amounts, say, '$100.00' is converted upon input to an 'internal' form of '10000' using the 'MR2' input processing code. A similar output processing code will re-display the figure as '100.00'. See the 'm' processing codes for all its variations.

One final reason for using an 'internal' format is to save storage space. Such an example would be to convert the external form of 'SMALL', 'MEDIUM', and 'LARGE' into 'S', 'M', and 'L'. The internal values can them be re-constituted upon output.