percent_weight adds 'Wt. %' to the arrow marker label as a suffix
weight_percent is an alias for percent_weight()
percent_atomic adds 'At. %' to the arrow marker label as a suffix
atomic_percent is an alias for percent_atomic()
percent_custom adds a custom suffix to the arrow label marker.
custom_percent is an alias for percent_custom()
percent_weight()
weight_percent()
percent_atomic()
atomic_percent()
percent_custom(x)
custom_percent(x)labs(W="XYZ").
T, L, R, W labels