Looks like the numbers are assigned randomly, see this discussion thread here on Reddit: https://www.reddit.com/r/USCIS/comments/yn60ig/decoding_ioe_case_numbers/. The creator of hilites Jin himself was in this thread, and he added a page on hilites for IOE I-140 cases, but it basically is a huge histogram with each bin height = 1... there is no way to analyze or visualize them, not like the way the SRC/LIN 140s are done.
It was not a priority to track these IOE 140s before because they were only a small fraction of all the 140s. But I think it'll become more and more important in the future for all the tracking websites, because more and more 140s will be assigned IOE receipt numbers. The majority of EB cases filed to SRC_SC are already assigned IOE receipt numbers in the past month (April 2023), you can see from the huge drop in the number of receipts of SRC_SC I-140s compared to before. Usually each month SRC_SC receives thousands (2000 - 4000) I-140 cases, but now it's around 750 in April 2023, so if we assume 3000 cases on average for SRC_SC, then (3000-750)/3000 = 75%, so probably 75% of SRC SC cases in April now have IOE receipt numbers and are not tracked.
This is most likely due to USCIS's effort of converting from paper-based EB processing to electronic-based. SRC_SC cases are at least 25% of all 140s, if all of them become IOE receipts, then you'll lose track of 25% of the I-140 statistics. If USCIS does the same for the other 3 centers, it'll be important to sift through all IOEs to single out I-140s in order to analyze them.