Fraunhofer lines are absorption lines in the Sun's optical spectrum that were identified centuries ago, being the easiest to detect. Some are revealed to be multiple lines by current spectral resolution, totaling thousands, that include (narrow) emission lines. Their original Fraunhofer line labels are uncommon now, but occasionally seen. Each label is a letter, optionally with a subscript, with upper-case an lower-case letters indicating different lines, with upper-case letters A through K for the prominent lines. Note that some are actually the result of Earth atmosphere, which affected all solar observation at the time of their discovery. Examples:
|D1||589.6||neutral sodium (Na I)|
|E||527.0||neutral iron (Fe I)|
|G||430.7||blended line from CH, iron, calcium, and others|
|H||396.8||ionized calcium (CA II)|
One term still seen occasionally is Fraunhofer's G band (or just G band) for the Fraunhofer G line, which was actually multiple lines of nearly the same wavelength in the vicinity of 429.5-431.5 nm. The term K-line is also still seen but is ambiguous because other incompatible uses of the term are now more common.