  The Simple Line Access Protocol (SLAP) is an IVOA Data Access protocol which
defines a protocol for retrieving spectral lines coming from various Spectral
Line Data Collections through a uniform interface within the VO framework.
These lines can be either observed or theoretical and will be typically used to
identify emission or absorption features in astronomical spectra. It makes use
of the Simple Spectral Line Data Model (SSLDM [1]) to characterize spectral
lines through the use of uTypes [14]. Physical quantities of units are
described by using the standard Units DM [15]. SLAP services can be registered
in an IVOA Registry of Resources using the VOResource [12] Extension standard,
having a unique ResourceIdentifier [13] in the Registry. The SLAP interface is
meant to be reasonably simple to implement by service providers. A basic query
will be done in a wavelength range for the different services. The service
returns a list of spectral lines formatted as a VOTable. Thus, an
implementation of the service may support additional search parameters (some
which may be custom to that particular service) to more finely control the
selection of spectral lines. The specification also describes how the search on
extra parameters has to be done, making use of the support provided by the
Simple Spectral Line Data Model (SSLDM [1])
