— Function: **LAG** (`variable`[`, n`])

variablemust be a numeric or string variable name.`LAG`

yields the value of that variable for the casenbefore the current one. Results in system-missing (for numeric variables) or blanks (for string variables) for the firstncases.

`LAG`

obtains values from the cases that become the new active dataset after a procedure executes. Thus,`LAG`

will not return values from cases dropped by transformations such as`SELECT IF`

, and transformations like`COMPUTE`

that modify data will change the values returned by`LAG`

. These are both the case whether these transformations precede or follow the use of`LAG`

.If

`LAG`

is used before`TEMPORARY`

, then the values it returns are those in cases just before`TEMPORARY`

.`LAG`

may not be used after`TEMPORARY`

.If omitted,

ncasesdefaults to 1. Otherwise,ncasesmust be a small positive constant integer. There is no explicit limit, but use of a large value will increase memory consumption.

— Function: **YRMODA** (`year, month, day`)

yearis a year, either between 0 and 99 or at least 1582. Unlike other pspp date functions, years between 0 and 99 always correspond to 1900 through 1999.monthis a month between 1 and 13.dayis a day between 0 and 31. Adayof 0 refers to the last day of the previous month, and amonthof 13 refers to the first month of the next year.yearmust be in range.year,month, anddaymust all be integers.

`YRMODA`

results in the number of days between 15 Oct 1582 and the date specified, plus one. The date passed to`YRMODA`

must be on or after 15 Oct 1582. 15 Oct 1582 has a value of 1.