Vikings general manager Rick Spielman has sliced potential candidates into 13 categories. While it won't have any impact on the search, what categories would the previous eight coaches fit under? And what one surprising category remains empty?

Former player with no coaching experience…

Norm Van Brocklin – The Hall of Fame quarterback was named as the franchise's first NFL head coach. He pulled a modern-day Jason Kidd and received a head coaching position right after he retired following the 1960 season with an NFL title and MVP honors.

You can cross off this box with a red Sharpie…unless this search is really thorough.

Canadian Football League coach with no NFL experience…

Bud Grant – This worked out well the only time the Vikings crossed the border looking for a head coach. Before Grant was named head coach in 1967, he led the Winnipeg Blue Bombers to four Grey Cup championships. The Hall of Fame coach retired, came back then retired again in 281 games with the Vikings with four Super Bowl appearances, 11 Central Division titles and 12 playoff appearances.

Hey, the Bears went this route last year with Marc Trestman. Just saying.

Offensive assistant on staff with no NFL head coaching experience…

Les Steckel – And you think Leslie Frazier had a short lease? Steckel was fired after one year in what some consider as the worst season in franchise history in 1984 (3-13). The wide receivers coach was Grant's successor after he retired and was the youngest head coach in the NFL at the time (38).

Offensive coordinator on staff with no NFL head coaching experience…

Jerry Burns – Grant's offensive coordinator finally got his chance after he retired for the second time. Named as the head coach in 1986, he went 55-46 overall in six seasons as the head coach. Burns led the team to six playoff games (3-3), including the 1987 NFC Championship game.

College coach with no NFL coaching experience…

Dennis Green – He spent three seasons as Stanford's head coach before becoming the first coach in franchise history to be hired from the college ranks. Green was named coach of the year in his first of 10 seasons (1992) with the Vikings. They earned four Central Division titles and two berths to the NFC Championship game under Green.

Offensive line/assistant head coach on staff that previously played for the franchise with no NFL head coaching experience…

Mike Tice – This is quite the category and one that will probably never see another candidate. Tice became the first Vikings head coach that previously played for the franchise when his tenure began in 2002. He spent four seasons after coaching the final game in 2001 with a 32-33 record. He made one trip to the playoffs.

Offensive coordinator from another team with no NFL head coaching experience…

Brad Childress – Out of all the categories listed, the next head coach could possibly fit here. Childress previously served as the Eagles' offensive coordinator before being named as head coach in 2006. He led the Vikings to consecutive NFC North titles in 2008-09 and lost 31-28 to the Saints in the 2009 NFC Championship game. He was fired after Week 11 in 2010.

Defensive coordinator on staff named interim head coach with no previous NFL head coaching experience…

Leslie Frazier – And we can cross off this category as well. Frazier was fired on Monday after taking over as interim head coach in 2010 for Childress. He finished 21-32-1 during his tenure with one winning record and playoff appearance last year (10-6).

So we have probably five legitimate categories Spielman probably has in his complicated concept of hiring the next head coach looking at the past. What's noticeably missing?

Former NFL head coach…

He said the research suggested there wasn't a category more successful than the other, but the Vikings have never hired someone with previous NFL head coaching experience. Spielman mentioned some of his categories during Monday's press conference and included former NFL head coaching experience a few times.

With a soft deadline of the Senior Bowl (Jan. 25) all these categories could make for a dragged out coaching search.