Output a DDI file for the survey

[Edouard-Legoupil]

DDI: https://www.ddialliance.org/ is the standard for survey meta-data and is used in survey catalog such as NADA: http://www.ihsn.org/software/nada

At the end of the data crunching process, we should have a function to generate a DDI file for the survey.

see some reference here: https://cran.r-project.org/web/packages/DDIwR/DDIwR.pdf
https://www.user2017.brussels/uploads/useR2017-brussel-nakano.pdf --

[Edouard-Legoupil]

Maybe find a way to input some HXL tag to the questions during the process... http://hxlstandard.org/standard/1_0final/dictionary/

[Edouard-Legoupil]

Attached is also a summary of the main DDI filed to mapped out
DDI-survey-Description.xlsx