Winter sales settings on Fnac.com:

10 € discount :

<promotion type="Sales">
<promotion_uid>[CDATA[]]</promotion_uid>
<sales_period_reference>WINTER_2021</sales_period_reference>
<starts_at>2021-01-20T00:01:00+01:00</starts_at>
<ends_at>2021-02-16T23:59:00+01:00</ends_at>
<discount_type>fixed</discount_type> 
<discount_value>10</discount_value>
</promotion>

10 % discount :
<promotion type="Sales">
<promotion_uid>[CDATA[]]</promotion_uid>
<sales_period_reference>WINTER_2021</sales_period_reference>
<starts_at>2021-01-20T00:01:00+01:00</starts_at>
<ends_at>2021-02-16T23:59:00+01:00</ends_at>
<discount_type>percentage</discount_type> 
<discount_value>10</discount_value>
</promotion>