# Date and Time Values

Dates and times are treated as numeric quantities, denoting the number of days elapsed since the date origin (usually 1-Jan-1904, or 1-Jan-1900 if the Use Excel date origin preference is checked). Dates can be entered directly into an expression, at any point in an expression and regardless of the number format setting, using the syntax d-MMM-yyyy, such as 27-Jan-2010, using a 3-letter English-language month abbreviation. Times can be entered in the format hh:mm:ss [tt], such as 10:27:00pm or 22:27:00, which becomes a fractional value between 0 and 1. A combined date-time can be entered as, e.g., 27-Jan-2010 10:27:00pm. In the general case, you cannot enter other date formats within an expression. For example, 1/27/2010 would be interpreted as two divide operators, (1/27)/2010, and regional (non-English) month names, e.g., 27-Ene-2010, are not recognized.

You can enter dates and times in more general formats, and in region/culture-specific styles, when the number format is set to Date and the date, time or date-time is the only element appearing in the expression. In this case, Analytica recognizes almost all commonly used formats, such as 27-January-2010, 1/27/2010, 1-27-2010, or Jan 27, 2010. When you enter a date in a format such as 1/2/2010 or 1-2-2010, the date is interpreted based on your regional setting. For example, in the US, these would parse to 2-Jan-2010, while in Europe they would generally parse as 1-Feb-2010. Non-English month names are also recognized in languages that use characters only from the standard Analytica character page (which includes most western European languages). For example, 27-Enero-2010 is recognized if you are in Spain.