"Item one: pick all the players who toured with the British and Irish Lions. Item two: pick the fit players we originally took to South Africa in the summer. Item three: pick the handful who were rested or injured then and are fit now. Item four: who's left?"
Okay, by the time the Scotland tour party had been thoroughly beaten and broken by some big, hard Samoans and Springboks, they had been forced into digging further into the barrel of reserves than even Scott Johnson, an eternal optimist, can have felt happy about. But if you look no further than the 30 players he had intended to use and add the usual suspects who were elsewhere, you just about have the training party he will name this afternoon.
There will be exceptions. On one hand, there's no point in bringing the likes of Ryan Wilson or Peter Horne along to the training camp since they are long-term injured and have no chance of being involved in the trio of internationals next month. On the other, there are a tiny number of players who were engaged in other things such as playing for the Under-20s in the summer, who deserve a call-up. Top of that list is the pair of youngsters Johnson himself name-checked earlier in the month. Mark Bennett, the 20-year-old centre, and Jonny Gray, the 19-year-old lock, have both been in outstanding form for Glasgow and both were good enough to win club selection for the opening Heineken Cup match in Toulon against the reigning champions. Maybe their inexperience was exposed during that game, but the fact is that they were there on form and will be in the national squad on the same basis.
One he is unlikely to name is Tommy Allan, who was with Scotland Under-20s in the summer but has been invited to train with Italy, where he was born to an Italian mother. As far as Johnson is concerned the decision is Allan's and at the moment it looks as though he is heading for Italy.
The other interesting question was one he will not have anticipated coming as early as it has done. Tyrone Holmes, the South African flanker whose father, Steven, hails from Peebles, has been peripheral in the Glasgow set-up but his man-of-the-match performance against Exeter at the weekend must have nudged him up the pecking order in a position where Scotland's strength is not as great as some think.
"To be selected would be a dream come true," he said. "But at the moment I just have to stay focused on getting back into the Glasgow starting line-up."
The real headache for Johnson is the core players who are short of match fitness after sitting out large chunks of the season.
Johnnie Beattie, the Montpellier No.8, is a particular problem. He deserves to keep his place for the courage he showed in the summer when he took on Italy with a badly damaged shoulder. On the other hand, he has not played for a month because of a torn pectoral muscle and had been mainly confined to bench duties before he was hurt.
Jim Hamilton, his clubmate who was also injured, is in a different category. He returned to action at the weekend, playing a solid 60 minutes, with two more rounds of matches before the internationals, and was getting a regular starting place before he turned his ankle.
From the weekend's action, only Max Evans picked up a serious-looking knock, going off after 28 minutes, but he has also been struggling for a starting spot and missed the summer tour so his place was by no means assured.
Of those who did stay at home in the summer, Nick De Luca, who was rested, played his way back into contention during Edinburgh's weekend match in France, while John Barclay, who was recovering from shoulder surgery, and Duncan Weir, who had broken his leg, have both been playing for three weeks.
More of an issue for Johnson are players such as Kelly Brown and Tom Heathcote, who have been fit and available but have been confined to bench duties at their clubs. Both are likely to be invited - Brown has been such a loyal servant to the national cause and Heathcote is the man in possession of the No.10 shirt - but may struggle to keep their positions when the team is pared to a match squad. "There will be two squads," explained Johnson. "There will be a [training] camp squad, which will be an extended one since this will be our first time together since the summer. Some have been away, some held back, so I will bring them all in so that they can all hear the same information about what we are trying to do. Then we will cull it as we go for each game."
So, when it comes to the big decisions, he will err on the side of inclusion and the long, intense selection meetings can wait until nearer the opening games.