What is L-band in DWDM

What is L-band in DWDM?
HyOptic offers 55 channels of DWDM L-band, from 1569.59nm to 1615.26nm.
L00 to L10, L56 to L99.

L-Band	Center Wavelength(nm)	F(GHz)
L 10	1569.59	191000
L 09	1570.42	190900
L 08	1571.24	190800
L 07	1572.06	190700
L 06	1572.89	190600
L 05	1573.71	190500
L 04	1574.54	190400
L 03	1575.37	190300
L 02	1576.20	190200
L 01	1577.03	190100
L 00	1577.86	190000
L 99	1578.69	189900
L 98	1579.52	189800
L 97	1580.35	189700
L 96	1581.18	189600
L 95	1582.02	189500
L 94	1582.85	189400
L 93	1583.69	189300
L 92	1584.53	189200
L 91	1585.36	189100
L 90	1586.20	189000
L 89	1587.04	188900
L 88	1587.88	188800
L 87	1588.73	188700
L 86	1589.57	188600
L 85	1590.41	188500
L 84	1591.26	188400
L 83	1592.10	188300
L 82	1592.95	188200
L 81	1593.79	188100
L 80	1594.64	188000
L 79	1595.49	187900
L 78	1596.34	187800
L 77	1597.19	187700
L 76	1598.04	187600
L 75	1598.89	187500
L 74	1599.75	187400
L 73	1600.60	187300
L 72	1601.46	187200
L 71	1602.31	187100
L 70	1603.17	187000
L 69	1604.03	186900
L 68	1604.88	186800
L 67	1605.74	186700
L 66	1606.60	186600
L 65	1607.47	186500
L 64	1608.33	186400
L 63	1609.19	186300
L 62	1610.06	186200
L 61	1610.92	186100
L 60	1611.79	186000
L 59	1612.65	185900
L 58	1613.52	185800
L 57	1614.39	185700
L 56	1615.26	185600