You may need to clean this area to see marks but if the knife is a Case, that's where you'll find the mark. Sometimes the price, 25c or 50c, was under the line.
The number 18 signifies the junior stockman pattern, a three-bladed knife and one of Case’s most popular.
The number at the end of the pattern stamp on a fixed blade knife usually signifies the blade length--thus, the numbers 65-5 signify a 5-inch bladed 65 pattern.
The blade abbreviation HPSS is a combination of HP (signifying that the knife has a sheep foot and a spay blade) and SS (signifying that the blades are stainless steel).
The abbreviation RAZDAM is a combination of RAZ (meaning “razor”) and DAM (meaning “Damascus steel”).
Look for distinctive elements on the tang stamp: the word Case XX; one or more dots; a series of dots and X's (for example, .x.x.) surrounding the word “Case”; or lightning-shaped S's.
The XX refers to the company’s proprietary two-step heating and two-step testing systems.
It would remove one dot per year for 10 years, such that a blade produced in 1970 had 10 dots, one produced in 1971 had nine dots, and so on. Absence of those elements dates your blade as pre-1940.
Locate the pattern stamp, a number of four or more digits and/or letters.
Case makes it easy, with a system of stamps, to identify a knife as an original Case and to identify it by its pattern, year of manufacture and composition of steel. (There may be one stamp on either side.) The stamps will be on the largest blade of a multiblade folding knife.
They are highly collectible—the Case Collectors Club has about 18,000 members, who collect by model (pattern), handle material and year among other characteristics.
Most knife manufacturers introduce some jigging pattern into handles, but Case has the largest variety and a few proprietary jigging patterns.