Fifa has opened disciplinary proceedings against England and Scotland for wearing poppies in Friday's World Cup qualifier.
Players from both countries wore black armbands bearing a poppy during England's 3-0 win at Wembley, with the game taking place on Armistice Day.
Rules forbid "political" statements on shirts.
Fifa, world football's governing body, would not "speculate on any outcome or provide an estimated timeline".
How did this situation arise?
The idea of players wearing a poppy was raised before the two nations met on 11 November, the day when the United Kingdom traditionally remembers those who have died in conflict.
According to the rule-making International Football Association Board (IFAB), which includes members of the four British football associations, players cannot wear "political, religious or personal slogans, statements or images".
The compromise of wearing a printed poppy on an armband was brokered for England's 1-0 friendly win over Spain at Wembley on 12 November, 2011.
In the same year, Scotland players wore poppies on armbands and on their tracksuits in a match against Cyprus.
However, world football's governing body would not specify before Friday's fixture whether England or Scotland would face punishment for doing so this time around.
What did the home nations say?
MP Damian Collins - chair of the Culture, Media and Sport select committee - wrote to Fifa president Gianni Infantino asking the world governing body to reconsider its decision.
English Football Association chief executive Martin Glenn said players from both sides would wear black armbands carrying the poppy "as a point of principle".
Meanwhile, chief executive of the Scottish Football Association Stewart Regan said before the match it was prepared to challenge any Fifa sanction imposed.
Fifa says it reminded the four football associations of the rules - though the Football Association of Wales (FAW) said Fifa "turned down a request for the Wales national team to wear poppies on their shirts or on armbands".
The FAW said it could not risk a financial penalty or point deduction.
What did Fifa say?
Fifa said it did not ban the display of poppies and that any such claim was "a distortion of the facts".
Football's rules are laid out by IFAB and any breach is dealt with by Fifa's disciplinary committee - which Fifa says is an independent body.
Fifa added it could not pre-judge what symbols would constitute a breach of rules.
However, Fifa secretary general Fatma Samoura told BBC Sport last week: "We have to apply uniformly and across the 211 member associations the laws of the game.
"Britain is not the only country that has been suffering from the result of war."
Fifa recently opened disciplinary proceedings over the Republic of Ireland's use of a logo to commemorate the centenary of the Easter Rising.
Possible sanctions?
A points deduction is the most serious sanction available but a fine is considered to be more likely.
The British FAs would then have an opportunity to challenge that fine via Fifa's appeals process and a further chance to appeal at the Court of Arbitration for Sport - a course of action that would probably cost more than the fine.
