Despite no underscore, I still get the underscore?

[ThomasColson]

Pro 2.4

[JoeBorgione]

A few more details could help for a response.

[ThomasColson]

3D Analyst -> Data Management -> Extract LAS

Right Click Batch

In Output LAS Dataset: "C:\Temp\LIDAR_TEST\LAS\LAS\%Name%_UNC.lasd"

However, all output LAS Datasets are named with an underscore at the beginning of the file name, which throws me off, I'm never a fan of a special character at the beginning of a file name. 

[JoeBorgione]

Sorry, I can't help at all- I currently don't have a 3d Analyst license available to even try it....

Kory Kramer‌ ?

[KoryKramer]

Tom, is the underscore added when the %Name% isn't a number?

[KoryKramer]

Something to the effect of 120054: is not a valid output name.—Help | ArcGIS Desktop 

[ThomasColson]

Hmmmmm you might be on to something. However, renaming all the las files is problematic, as getting the correct tile # is important, and adding characters throws off downstream tools that generate a raster which has a length restriction in the name.