By BARBARA ORTUTAY and MATT O’BRIEN
AP Technology Writers
Could technology companies have monitored ominous messages made by a gunman who Texas authorities say massacred 19 children and two teachers at an elementary school? Could they have warned the authorities? Answers to these questions remain unclear, in part because official descriptions of the shooting have continued to evolve. For instance, on Thursday Texas officials made significant revisions to their timeline of events for the shooting. But the shooting in Uvalde, Texas, seems likely to focus additional attention on how social platforms monitor what users are saying to and showing each other.