Silly me, I've answered my own question. The issue was not with the stylesheets or my customization layer, but rather with oXygen.
Apparently oXygen set up some parameters in the transformation scenarios that were overriding my own stylesheets. After removing those parameters, this problem (and a few other oddities) were fixed.
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David Goss, Technical Writer
Frontier Science | www.fstrf.org
4033 Maple Rd, Amherst, NY 14226
(716) 834-0900 extension 7218
From: "David Goss" <goss@fstrf.org>
To: docbook-apps@lists.oasis-open.org
Sent: Wednesday, February 26, 2014 11:48:51 AM
Subject: Turning off admonition graphics
I would like for admonition graphics to not be displayed in both HTML and PDF output. Based on the documentation, this seems to be a trivial thing to accomplish. I simply set the following in my customization layers:
<xsl:param name="admon.graphics" select="0"/>
And yet, the admonition graphics are still appearing in both HTML and FO output. Is this a bug in the 1.78.1 stylesheets? I actually thought the stylesheets were supposed to default to *not* displaying the admonition graphics?
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David Goss, Technical Writer
Frontier Science | www.fstrf.org
4033 Maple Rd, Amherst, NY 14226
(716) 834-0900 extension 7218