Is there any particular pattern as to when a Sesame function, etc., will begin with @ and when not? I note that when there is both a command that sets something and a function that returns the value--e.g., ClientLocalValue() and @ClientLocalValue()--the one that returns the value will have an @.  But other times it seems random, e.g., @Right, @Left but ToLower and ToUpper.

(Or is it like a Quiz Discover Magazine had years ago where they asked the relationship among a bunch of seemingly random numbers?  People sent in all sorts of complex formulas that purportedly generated the set.  The correct answer was that they were the Express stops for a particular New York City subway line!)

I hadn't thought about it from a QA vs. Sesame perspective. That makes a lot of sense.  (I'm a newbie with Sesame and never worked with QA programming and I am constantly adding @ to ToUpper and forgetting to put it with @Left and @Right.)

Bob is essentially correct, we inherited some conventions and inconsistencies from Q&A. We also developed a couple of our very own. In general, functions use the leading "@" and subroutines do not. In any case, here is a quick list of the exceptions (derived by a glance, so there may be a couple of misses):

Subroutines having a "@":
=================
@msg( s as string )
@ditto( var ... as string )
@help( var fieldName as string )
@play( ... as string )
@color( var fieldName as string, textColor as int, backgrColor as int )
@save()
@exit()
@fedit()
@macro( mname as string )
@deferredmacro( mname as string )
@msgBox( x as string, y as string, z as string )

Functions without a "@":
================
readchar() as char
fileOpen( fileName as string ) as int
fileSize( handle as int ) as int
filePos( handle as int ) as int
fileReadChar( handle as int ) as char
fileGetLastError() as int
fileGetErrorMsg( errorCode as int ) as string
fileExists( fileName as string ) as boolean
dims( var a as array ) as int
dimLimit( n as int, var a as array ) as int
elementType( var a as array ) as string
intElement( var a as array, ... as int ) as int
doubleElement( var a as array, ... as int ) as double
moneyElement( var a as array, ... as int ) as money
booleanElement( var a as array, ... as int ) as boolean
charElement( var a as array, ... as int ) as char
dateElement( var a as array, ... as int ) as date
timeElement( var a as array, ... as int ) as time
stringElement( var a as array, ... as int ) as string
tab( n as int ) as string
split( var s as string, delimiters as string ) as string
random( n as double ) as double
toUpper( s as string ) as string
toLower( s as string ) as string

The "test" command is a real life-saver, as is the List Browser.