Custom markers on X or Y axes of charts

I primarily deal with time-series data, which usually involes line charts, vertical bar charts, or combination charts. Often when dealing with time series data you want to be able to track the occurrence of specific events to designate that something of interest occurred at a particular time to inform later analysis.

I would like to be able to define custom markers on the Y axis (time) in order to indicate that particular events occurred on those dates. Being able to do so would help make later analysis easier.

At a minmum I'd like to be able to put vertical lines at year divisions, but I'd like to be able to track events like "Hardware Failure", "Script Crashed", "Network Down", etc. in order to understand why certain time periods are busier than others.