The following works like you would think:

[when]xxx

{l:ENUM:MyBean.l} {x:ENUM:MyBean.x} {y:ENUM:MyBean.y}=eval($sep.foo("any", "any", "{l}

", "

{x}", "{y}", "", ""))

Defect 1
If you remove the spaces between the "} {"
[when]xxx {l:ENUM:MyBean.l}{x:ENUM:MyBean.x}{y:ENUM:MyBean.y}=eval($sep.foo("any", "any", "{l}", "{x}

", "

{y}

", "", ""))

l = ""
x = ""
y = l + x + y

Defect 2
Even in the first case, if the Enumeration returns a value that has space(s) in it (which maybe should not be allowed?) it will make for odd substitutions as well.

Note that I need spaces to be supported.

Defect 3
Regardless of the date format specified the substitution always dd-MMM-yyyy

{startTime:DATE:"dd-MMM-yyyy HH:mm"} {startTime:DATE:"dd-MMM-yyyy:HH:mm"} {startTime:DATE:"dd-MMM-yyyy@HH:mm"} {startTime:DATE:"HH:mm"}

all result in "25-Feb-2014"