Type u (LDF-Controlled Format) and ||u (ignore LDF) have varying effects on dates, times, Y/N and numeric fields whose format options may vary based on the Language Definition File (LDF). Note that unlike most type codes which act independent of the order they appear in, u and ||u must generally precede the associated type codes.
For date fields (D, d, and U), u has no effect. The D and d date fields use the LDF format by default, and the European date (U) fields always use the European format. The only LDF-related option here is to precede the D or d with ||u to force the American format even when the LDF specifies European format. (That could be a useful workaround for running a USA-developed app, which assumed American date format, in some other part of the world.) Note that a good strategy for avoiding confusion within an application related to differing date formats is to always add the > code to force {CC}YYMMDD format internally, regardless of the display and edit format. Also note that in a GUI environment where a date-specific control (such as a calendar control) is being used, the edit/display format will generally be determined by the regional settings of the client PC (making the > option even more important.)
For Y/N fields, the affirmative and negative characters are determined by the LDF, unless you precede the type Y or YN with ||u, in which case it will use "Y" and no "N". In the GUI environment, you may want to use type ||c to convert your Y/N fields to checkboxes (which avoids all language and regional confusion).
For numeric fields (#, H, $), u forces INFLD to use the decimal point and thousands separator characters specified in the LDF, rather than the USA default characters ("." and "," respectively). In this case, the u does not have to precede the numeric type code.
Note that this will only have an effect if the field would otherwise allow entry or display of decimals and thousands separators. See type codes . , M, $, H as well as the defpt and maxpt parameters.
See Also
The system parameter LANGUAGE for establishing the LDF, and GTLANG for how to query it.
