---
title: "Is the municipality BfS Nr. unique over time?"
date: "`r format(Sys.Date(), '%d.%m.%Y')`"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Is the municipality BfS Nr. unique over time?}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r setup, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

library(SMMT)

```




No.


# Example

The bfs_nr 3955 belongs to the municipalitiy Landquart (GR). Until October 1977, this bfs_nr 3955 was also in use but for different geographical entity, namely the "Gemeindefreies Gebiet Maienfeld-Fläsch".

# Consequence 

To join two datasets of two different time periods, one might think that the bfs_nr can be used to do the join. However, this is not possible because the bfs_nr can be reattributed over time. Thus, a simple bfs_nr based join is not possible. 


