oozie intial instance and start time giving error on missing dataset

Question

I am new to oozie and trying to understand dataset.xml. I have following dataset and trying to understand what exactly oozie is trying to validate here. what is the meaning of initial instance and what uri-template is doing here(not clear on oozie document)

<dataset name="sample" frequency="${coord:hours(1)}" initial-instance="2022-01-10T00:00Z" timezone="UTC">
        <uri-template>${hdfsdir}/filepath/${YEAR}${MONTH}${DAY}${HOUR}</uri-template>
        <done-flag>_SUCCESS</done-flag>
 </dataset>

Similarly, in coordinator I have following for input and output dataset. Here what is the significance of current(-5) and start parameter?

<coordinator-app name="test" frequency="${freq}" start="2022-01-10T00:00Z" end="2023-04-11T00:00Z" timezone="UTC" xmlns="uri:oozie:coordinator:0.4" xmlns:sla="uri:oozie:sla:0.2">
 
  <data-in name="raw" dataset="raw_data">
            <instance>${coord:current(-5)}</instance>
   </data-in>

<data-out name="processed" dataset="raw_out">
                <instance>${coord:current(-5)}</instance>
       </data-out>

Can someone explain what oozie is expecting on the datasets?

Thanks, bab