The general consensus and the often repeated statement is that Manny Pacquiao won the flyweight lineal title when he defeated Chatchai Sasakul in 1998. Before you say "of course he was" based on hearsay, please check out this timeline.
This was in the years where The Ring did not declare Ring Champions, so one must look at the rankings for that year. The Ring recognized the #1 and #2 as lineal champions while not giving a belt.
Flyweight rankings during 1990's:
The consensus top flyweight thru 1998 was Mark Johnson, whom moved up to 115 lbs in his April 1999 fight.
Sasakul, listed in the above link as "Chatchai Gym" was #2 behind Johnson at the end of the 1997 calendar year.
Pacquiao's only win to get him on the list would be over Chockvivat in 1997. Chockvivat never ranked higher than Ring #10 at the weight.
Going into their 1998 showdown, Sasakul was the Ring #2 ranked flyweight while Pacquiao was somewhere maybe in the top 10, maybe not. If someone has the relevant Ring Mag issues from 1998, please clarify this.
At the end of the 1998 year, Ring magazine ranked Pacquiao #1 and Sasakul dropped to #4 after the loss to Pac. However, these rankings excluded Mark Johnson as he was now about to campaign at 115 lbs.
Here are Johnson, Sasakul, and Pacquiao's boxrec's, respectively:
So, please explain if you believe Sasakul vs. Pacquiao was for the lineal title, technically speaking and in your opinion.
My answers would be: No and No, but perhaps the postings of month by month rankings and justifications by The Ring would make me change my mind on the former. Edit: Obviously, the lineage is very legitimate. I had a hard time tracing back and honestly feel foolish for starting the thread. It is a very interesting lineage to trace though... Go Canto! Go Pacquiao!