The "22" denotes the model number. The pre-fix "S" or "DL" denotes whether a "standard" model or a "deluxe" model. This is some what misleading because the what we think of as the "classic" Raleigh Sports with its westrick rims, double-ended cables/calipers, and other features was being called a "deluxe" model. The "s" for "standard" was a more economy model in between the cheaper Phillips/Hercules offerings and the classic Sports.
The 1963 US price list sets the S22 with AW hub at $54.95. That would be a little over $570.00 in current money. At $64.95, the DL22 Sports was a more expensive bike (about $674 in today's money).
The S22 was a little cheaper all the way around: Endrick rims instead of Westrick, XPT kickstand instead of the better Raleigh stand, cheaper calipers, cheaper levers, cheaper saddle, cheaper tires, etc.
The cheapening program of the 1960s meant that Raleigh began to emphasize the classic Sports as a "deluxe" bike and this sort of cheaper bike as the "standard". In a sense, it was a debasing of the Raleigh currency - making the normal seem "deluxe" and the cheaper seem "standard". Raleigh also was increasingly in competition in the US market with cheaper imports under Sears, Royce Union, JC Penney, Steyr, etc.
The tab on the stem appears to be the broken-off remnant of an aftermarket stem-top lamp bracket.
From the 1963 Raleigh USA price list -
View attachment 2174810
Edit: this is not to use the word "cheap" in a derogatory way. The S22 is a decent bike. It's more about Raleigh/TI trying to cut costs without taking as much of a hit to its premium reputation.