Citrix Systems 9.2 Dates and Times in a Rewrite Action, Expressions for the NetScaler System Time

Chapter 5 Advanced Expressions: Working with Dates, Times, and Numbers 97
When you specify a date and time, note that the format is case sensitive and must
preserve the exact number of blank spaces between entries.
Note: In an expression that requires two time values, both must use GMT or both
must use LOCAL. You cannot mix the two in an expression.
Dates and Times in a Rewrite Action
Unlike using the SYS.TIME prefix in an advanced policy expression, if you
specify SYS.TIME in a rewrite action, the NetScaler returns a string in
conventional date format (for example, Sun, 06 Nov 1994 08:49:37 GMT). For
example, the following rewrite action replaces the http.res.date header
with the NetScaler system time using a conventional date format:
add rewrite action sync_date replace http.res.date sys.time
Expressions for the NetScaler System Time
The SYS.TIME expression prefix extracts the Netscaler system time. You can
configure expressions that establish whether a particular event occurred at a
particular time or within a particular time range according to the NetScaler
system time.