# Summary 

`aion` is designed to provide a consistent framework for representing 
archaeological time series that can extend very far in the past.
`aion` provides a system of classes and methods to represent and work
with such time series. This package does not provide tools for temporal analysis or 
modeling. Instead, it offers a system of classes and methods to represent and 
work with archaeological time series. This API can be extended and used by other 
specialized packages (see `kairos` v2.0 as an example).

# Statement of need

R ships with a lot of functionality useful for time series, in particular 
in the base `stats` [@R-stats], or in the `zoo` [@R-zoo] packages[^1]. 
However, these features are not adapted to most archaeological time series. 
At the same time, numerous R packages have been developed to describe, analyze, and model 
temporal data in the context of archaeological studies in the broadest sense. 
These packages encompass various functionalities, including handling radiocarbon 
data (e.g., `Bchron` by @R-Bchron or `rcarbon` by @R-rcarbon), Optically 
Stimulated Luminescence dating (`Luminescence` by @R-Luminescence), Bayesian 
chronological modeling (`ArchaeoPhases` by @R-ArchaeoPhases), 
using paleoenvironmental proxies (e.g., `shoredate` by @R-shoredate), or other 
temporal data (e.g., `kairos` by @R-kairos). This multitude of packages 
underscores the significance of computational approaches in archaeology 
[@schmidt2020]. However, it also presents a major challenge as each package 
employs its own representation of temporal information. Consequently, exchanging 
data between different packages within the same data workflow becomes even more 
arduous.

Archaeological data is typically collected through field excavations or 
surveys, resulting in irregularly spaced observation times. Although several 
packages can handle irregular time series, the way they represent dates means 
they cannot easily be used for archaeological series. These are indeed defined 
for a given calendar era and more importantly they can involve dates very far 
in the past.