The saccharides are divided into four chemical groups&colon; monosaccharides, disaccharides, oligosaccharides, and polysaccharides. These often include fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs). All monosaccharides are reducing sugars, along with some disaccharides, some oligosaccharides, and some polysaccharides. Longer chains of monosaccharides are not regarded as sugars, and are called oligosaccharides or polysaccharides. Methods for the structure determination of oligosaccharides and polysaccharides include NMR spectroscopy and methylation analysis. Flatulence-producing foods are typically high in certain polysaccharides, especially oligosaccharides such as inulin. Two, three, several or many monosaccharides thus linked form disaccharides, trisaccharides, oligosaccharides, or polysaccharides, respectively. Not all natural oligosaccharides occur as components of glycoproteins or glycolipids. Here monosaccharides, oligosaccharides, and polysaccharides are the compounds of interest. Milk contains several different carbohydrate including lactose, glucose, galactose, and other oligosaccharides. Calnexin binds only those N-glycoproteins that have GlcNAc2Man9Glc1 oligosaccharides. Other amylase enzymes may convert starch to glucose or to oligosaccharides. All "N"-linked oligosaccharides are pentasaccharides&colon; five monosaccharides long. Glycolipids are lipid molecules bound to oligosaccharides, generally present in the lipid bilayer. For example, phosphorylation of oligosaccharides on lysosomal proteins occurs in the early CGN.