If you want to assign some default value to a parameter of type VARCHAR in a stored procedure and the parameter value does not have any spaces then the quotes around the value are optional.
create procedure TestProc ( @a varchar(20) = 'spaces in string', --must use quotes for string with spaces @b varchar(20) = 'nospacesinstring', @c varchar(20) = nospacesinstring --quotes are optional if no spaces in string ) as select @a, @b, @c; ; exec TestProc;