Explanations
Abbreviations are often used in chord names (alternative chord symbols in parentheses).
Gb - G flat major (Gb△)
Gbm - G flat minor
Gb7 - G flat dominant seventh
Gbm7 - G flat minor seventh
Gbmaj7 - G flat major seventh (Gb△7)
GbmM7 - G flat minor major seventh
Gb6 - G flat major sixth
Gbm6 - G flat minor sixth
Gb6/9 - G flat sixth/ninth (sixth added ninth)
Gb5 - G flat fifth
Gb9 - G flat dominant ninth
Gbm9 - G flat minor ninth
Gbmaj9 - G flat major ninth
Gb11 - G flat eleventh
Gbm11 - G flat minor eleventh
Gb13 - G flat thirteenth
Gbm13 - G flat minor thirteenth
Gbmaj13 - G flat major thirteenth
Gbadd - G flat add
Gb7-5 - G flat seven minus five
Gb7+5 - G flat seven plus five
Gbsus - G flat suspended
Gbdim - G flat diminished (Gb°)
Gbdim7 - G flat diminished seventh (Gb°7)
Gbm7b5 - G flat minor seventh flat five (Gbø)
Gbaug - G flat augmented (Gb+)
Gbaug7 - G flat augmented seventh