Split Chess World Championships. How did that work

I have a question regarding the period during which the Chess World Champion Titles were split. I noticed that Anand challenged Kasparov for the PCA World Chess Championship in 1995, and then later challenged Karpov for the FIDE world title.

How did that work? Were players free to play either candidates tournaments? Did FIDE not mind one of their players challenging for the rival world championship? Were sanctions imposed on Anand by FIDE?

Were there seperate candidates' tournaments  for both championships?

An explanation would be very welcome. Thank You

Long story.

FIDE stripped Kasparov and Short of their champion and challenger titles, and temporarily removed them from the Elo Rating list.  Players from a few federations were invited to play in the PCA Interzonal and Candidates.  Kasparov and Short's names are missing from the two 1994 FIDE Rating lists, but they were added back for the January 1995 list.  I don't think FIDE imposed any sanctions against other players.

The PCA organized Interzonals, Candidates matches and a world championship match 1994-1995, but Intel pulled out as a sponsor in 1996, and the organization fell apart.

The FIDE Zonal Interzonal Candidates cycle continued as usual, just without Kasparov and Short for 1993-5.  Short played in a FIDE Interzonal and Candidates match in 1997.

Anatoly Karpov refused to play in FIDE's 1999 world championship knockout tournie, but he did join for the 2001 championship.

Kasparov's 1990 match vs. Karpov was his last time playing in a FIDE cycle, although he was in negotiations to play a match against Ponomariov or Kasimdzhanov, the FIDE champions 2003-4.  Ponomariov was unhappy with FIDE's proposed conditions, and Kasparov retired from playing before funding could be found for a match with Kasimdzhanov.

Kramnik refused to play in the FIDE cycles from 2000-2005, but he rejoined for a 2006 title match vs. Topalov.