On Fri, 14 Jun 2019 20:10:15 -0700, pyotr filipivich
wrote:

DerbyDad03 on Fri, 14 Jun 2019 19:04:46 -0700
(PDT) typed in rec.woodworking the following:
On our recent trip to Oregon we walked along the docks in Astoria, right
near the original Bumble Bee Tuna cannery on the Columbia River.

All of the wood on the docks, the railings and even the railroad ties
look like the following. There was a mixture of old wood and new and it
all looked like this:

https://i.imgur.com/IOgfmsB.jpg

Do the "dashes" serve a purpose? Are they perhaps marks from where
preservative was injected?

Yes.
Here is an answer taken right off of the CWC webpage:




Incising is the process of cutting many small slits into the surface
of a piece of wood in order to increase the amount of preservative
taken up by the wood during treatment. Some wood species are
particularly hard to treat, and incising is necessary to meet the
penetration requirements in CSA standards. Non-incised CCA-treated
wood will have a shorter service life than incised CCA-treated wood,
but the difference may not be noticeable in the short term (under 20
years) in relatively low decay hazards such as decking. For wood in
critical structural applications under conditions conducive to decay,
incising could make the difference between 4 and 40 years service.
Incising is not necessary with borate-treatment, because borate
diffuses to achieve the required penetration. With borate-treated
wood, there in no difference in performance between non-incised and
incised, provided the target chemical content is achieved. There is a
strength-loss penalty for incising, which is addressed during
structural design.

The slits or incisions are on all 4 sides in any lumber I have seen