TripleD: Construct a TripleD database.

#' Attributes for CSV input files TripleD database
#'
#' Data frame with information on all attributes that should or could be
#' included in the CSVs that act as input for the formation of the database.
#'
#' @name attributes
#' @format A dataframe with the following columns:
#' \describe{
#' \item{\code{Attribute}}{The name of the attribute as it should be used as column name in the CSV.}
#' \item{\code{Unit}}{The unit the attribute should have.}
#' \item{\code{Required_or_Optional}}{Whether or not the attribute is required.
#' If this is filled with 'Required_alternative' it means the information is required, but can be given in different ways.}
#' \item{\code{Group}}{Sometimes attributes belong together, these are grouped.}
#' \item{\code{Datatype}}{The datatype of the values (integers, fractions, doubles, strings, etc.)}
#' \item{\code{Description}}{Perhaps the most important column. This contains an eleborate
#' description of what the information of this attribute includes; how data should be documented.}
#' }
#' @details TripleD data is summarized per cruise in CSVs that can be read by
#' the package in order to create a database. These CSVs either contain station
#' or species data. The format of these CSVs, thus, the names of all variables
#' and the exact meaning of the values in those columns, is explained here.
#' \cr
#' A dataframe exists for the station CSVs called 'att_stations' and for the species
#' CSVs called 'att_species'.
#' \cr
#' It is also possible to include data to convert sizes and wet weights to ash-free dry weights.
#' This data should be included in a file called 'bioconversion.csv'.
#' The requirements for this file can be found in 'att_bioconversion'.
#' \cr
#' The meaning of all columns in the final two databases produced by the package can be found
#' in 'att_database' and 'att_database_individuals'.
NULL

#' @rdname attributes
"att_stations"

#' @rdname attributes
"att_species"

#' @rdname attributes
"att_bioconversion"

#' @rdname attributes
"att_database"

#' @rdname attributes
"att_database_individuals"