diff --git a/Makefile b/Makefile
index 200360f0a..c731eac92 100644
--- a/Makefile
+++ b/Makefile
@@ -83,6 +83,7 @@ OPTIONS := --trace \
            -a mathematical-format=svg \
            -a pdf-fontsdir=docs-resources/fonts \
            -a pdf-theme=docs-resources/themes/riscv-pdf.yml \
+           -a docinfo=shared \
            $(XTRA_ADOC_OPTS) \
            -D build \
            --failure-level=ERROR
diff --git a/src/docinfo.html b/src/docinfo.html
new file mode 100644
index 000000000..ac70253be
--- /dev/null
+++ b/src/docinfo.html
@@ -0,0 +1,22 @@
+<style>
+/*
+Any ID starting with 'qx_' (arbitrarily chosen to be unlikely to
+be used by accident) is a snippet of specification text that has been
+specifically tagged to allow referencing it robustly, for use cases
+such as:
+
+* Linking coverage, tests plans, tests, assertions etc. to parts of
+  the spec that they cover.
+* Detecting when parts of the spec change. You can extract these
+  snippets via Asciidoc's docbook output and parsing the XML.
+* Linking documentation (e.g. the implementation defined parameter list)
+  to the spec.
+  
+This adds a subtle decoration to make it easier to find tagged text.
+*/
+[id^="qx_"]:hover {
+    text-decoration: underline;
+    text-decoration-style: dotted;
+    text-decoration-color: gray;
+}
+</style>
diff --git a/src/rv32.adoc b/src/rv32.adoc
index 86f636ec9..0bbedb3cb 100644
--- a/src/rv32.adoc
+++ b/src/rv32.adoc
@@ -40,7 +40,8 @@ Most of the commentary for RV32I also applies to the RV64I base.
 
 <<gprs>> shows the unprivileged state for the base
 integer ISA. For RV32I, the 32 `x` registers are each 32 bits wide,
-i.e., `XLEN=32`. Register `x0` is hardwired with all bits equal to 0.
+i.e., `XLEN=32`.
+[#qx_x0_is_zero]#Register `x0` is hardwired with all bits equal to 0.#
 General purpose registers `x1-x31` hold values that various
 instructions interpret as a collection of Boolean values, or as two's
 complement signed binary integers or unsigned binary integers.