Export order of block randomization

Hello, in a survey of mine, I have used randomized blocks. I now want to see in which order respondents have been presented with the blockand have enabled "export viewing order data for randomized survey" when exporting my data, but I'm struggeling to understand the extra columns. I do understand that "1|2|3" in "Block1_DO" means that the respondent has seen question 1 first, then question 2 and then question 3 in Block1. However, what do the columns starting with "FL_" mean? Do they refer to block randomization? Any help is appreciated, thanks!