Just a quick tip since I didn’t find this to be well documented anywhere and someone else probably has this exact same problem.  Frequently, I display time and date on a page.  I used to do it like so:

#dateFormat(now(),'dddd, mmmm d, yyyy')# at #timeFormat(now(),'h:mm tt')#

…but why use two functions when you can use one, right?  So I tried using the following:

#dateTimeFormat(now(),'dddd, mmmm d, yyyy at h:mm tt')#

But got briefly stuck when the ‘t’ in the date mask was getting translated to “apm” instead of the literal “at”.  I said to myself, “Self… you need to escape those literal characters.”  I came up with this:

#dateTimeFormat(now(),'dddd, mmmm d, yyyy "at" h:mm tt')#

But received the same result.  As it turns out, in this case, double quotes and single quotes are important.  The quick tip here is: escaping literal characters in a dateTimeFormat() mask requires the use of double quotes outside the mask and single quotes to escape your literal characters.

The winner was the following:

#dateTimeFormat(now(),"dddd, mmmm d, yyyy 'at' h:mm tt")#