Hydrogenated starch hydrolysates (HSHs), also known as polyglycitol syrup (INS 964),  are mixtures of several sugar alcohols (a type of sugar substitute). Hydrogenated starch hydrolysates were developed by the Swedish company Lyckeby Starch in the 1960s. The HSH family of polyols is an approved food ingredient in Canada, Japan, and Australia. HSH sweeteners provide 40 to 90% sweetness relative to table sugar. 
Hydrogenated starch hydrolysates are produced by the partial hydrolysis of starch – most often corn starch, but also potato starch or wheat starch. This creates dextrins (glucose and short glucose chains). The hydrolyzed starch (dextrin) then undergoes hydrogenation to convert the dextrins to sugar alcohols.
Hydrogenated starch hydrolysates are similar to sorbitol: if the starch is completely hydrolyzed so that only single glucose molecules remain, then after hydrogenation the result is sorbitol. Because in HSHs the starch is not completely hydrolyzed, a mixture of sorbitol, maltitol, and longer chain hydrogenated saccharides (such as maltotriitol) is produced. When no single  polyol is dominant in the mix, the generic name hydrogenated starch hydrolysates is used. However, if 50% or more of the polyols in the mixture are of one type, it can be labeled as "sorbitol syrup", or "maltitol syrup", etc.