When we make a back loop stitch (“st in BLO”), the front loop of this stitch stays free. We will use this free front loop in a later round to ‘anchor’ a stitch (“st in FLO”).
Example with numbers:
Stitches you make in the current round are stitches in ‘Round 0’.
The stitches you made in the previous round are stitches in ‘Round -1’.
A stitch you work in BLO in the current round (0-0) leaves a free front loop from the stitch in the previous round (0-1). The front loop belongs to the stitch from ‘Round -1’. In the next round, this will be a free front loop of the stitch from ‘Round -2’ – the FLO of the st 2 rounds below. (0-2).