  The emission lines emitted from gaseous nebulae carry valuable information
about the physical conditions and chemical abundances of ionized gases in these
objects, as well as the interstellar extinction. "proEQUIB" is a library
containing several application programming interface (API) functions developed
in the Interactive Data Language (IDL), which can be used for plasma
diagnostics and abundance analysis of nebular spectra. This IDL library can
also be used by the GNU Data Language (GDL), which is a free and open-source
IDL compiler. This package includes several API functions to determine physical
conditions and chemical abundances from collisionally excited lines (CEL) and
recombination lines (RL), derive interstellar extinctions from Balmer lines,
and deredden the observed fluxes. This IDL library heavily relies on the IDL
Astronomy User's library and the IDL "AtomNeb" library. The API functions of
this IDL library can easily be utilized for spatially-resolved studies of
ionized gaseous nebulae observed using integral field spectroscopy.
