510 fence on a 520?

[EYoung]

I just purchased a 520 from a widow. It was well taken care of and I hope to do the same. I can tell the former owner was a man of precision and care by looking at how well he maintained his machine and how tight his joints were. It included a 510 fence in addition to the 520 fence. When I asked if he had upgraded his wife said no and she had the original bill of sale. Given all this evidence I feel like the 510 fence is not just a leftover piece and must have served some purpose on his 520.

Can you think of what a 510 fence would be used for on a 520 fence system?

It only came with a jointer, miter pro, dust collector and shaper attachments.

[JPG]

Perhaps it was purchased in error?

[dusty]

I know of no way that a 510 fence cold be used in/on a 520 configuration. The rail system prohibits that. However, he might have had visions of a second machine (or application) that would utilize a 510 fence; understanding that a 510 fence (unless utilized as parts) must be used in conjunction with a 510 rail system.