Zemeljski plin s faktorjem λ-premika med 0,89 in 1,08 (0,89 ≤ Sλ ≤ 1,08) spada v razred H, zemeljski plin s faktorjem λ-premika med 1,08 in 1,19 (1,08 ≤ Sλ ≤ 1,19) pa v razred L.
Natural gases with a λ-shift factor between 0,89 and 1,08 (0,89 <= Së <= 1,08) are considered to belong to H-range, while natural gases with a ë-shift factor between 1,08 and 1,19 (1,08 <= Së <= 1,19) are considered to belong to L-range.