Ken,
Thanks for clarifying!
I completely agree that it is within the purview and responsibility of the describer to make sure they tell the story appropriately. And as is obviously the case for the contacts / restrictive features, boundary distinctness/topography and the likely variability across the landscape certainly need to be taken into account when grouping soils for interpretations.
Ultimately ST's (or any classification system's) utility relies on a relatively unambiguous set of characteristics for defining class membership. While it is always important to use proper professional judgment to ensure we communicate that pedon's place in our soil-landscape model, I do think it is just as important that taxonomic limits be encoded unambiguously (assuming the needed data are available). We have the concept of similar soils to deal with situations where taxonomic groups don't align with interpretive groups. I may be going to far here, but I think it is perhaps too much burden to place on ST to be able to also be used as similar soils criteria -- something that can vary tremendously from place to place. ST suggests where soils will be different, in general, but not where they are similar. Similar soils rightly requires more fuzzy reasoning than is appropriate for a classification system.
We ultimately have to put the breaks somewhere. If we have defined "tie breaking" logic, we need only describe it what the pedon is, and it then it keys out how it keys out. When the breaks are well defined, it is relatively easy to evaluate the classification system in its current form as well as the downstream effects of proposed changes.
Regardless, the issue I intended to raise here was not with any particular taxonomic limits ... but rather that I didn't think "within" was clearly defined. As I suspected, there was an intended meaning. I'd love to see a clarifying statement in the appropriate spot. And perhaps a clarification of the intent of breaks in the Soil Depth Class Key, where it appears to exclude the given depth from the range using "less than".
Thanks for taking the time to respond! I'm excited to have a good justification (aside from "I just think this is what they meant") for using <= for these types of ST clauses in my pedon classification script.
Andrew
