How to specify symbol/character in os-signpost-point-schema - xcode

Question

I have a custom Xcode 13.2.1 (13C100) Instrument to which I have recently added os-signpost-point-schema. I notice that the events are marked with a hyphen/dash rather than a ⓢ. See the comparison of my custom tool vs the standard “Points of Interest” tool:
I have been digging through the documentation and while I wager that there is some simple attribute that can be set to dictate which symbol is included within the signpost ⃝, it is not jumping out at me. How does one select the symbol used within custom event points in Instruments?
Here is the code for the instrument:
<?xml version="1.0" encoding="UTF-8" ?>
<!-- Instruments Developer Help: https://help.apple.com/instruments/developer/mac/current/ -->
<package>
<id>com.robertmryan.CustomInterval</id>
<version>0.2</version>
<title>Custom Points of Interest</title>
<owner>
<name>Robert Ryan</name>
</owner>
<import-schema>os-signpost</import-schema>
<!-- See https://help.apple.com/instruments/developer/mac/current/#/dev536412616 -->
<os-signpost-point-schema>
<id>custom-point-schema</id>
<title>Points</title>
<owner>
<name>Robert Ryan</name>
</owner>
<purpose>Provide mechanism for multicolored events posted by `os_signpost`; The string generated by `os_signpost` must be in form of "Label:%d,Concept:%{public}#", where "Label" is string that will control what text appears in the event, and "Concept" is one of the strings listed in https://help.apple.com/instruments/developer/mac/current/#/dev66257045 that dictates the color of the interval. No spaces after the commas within this string.</purpose>
<note>That message must use that printf-style format, not embedding the values in the format string literal.</note>
<!-- you can constrain this to a particular subsystem if you'd like:
<subsystem>"com.domain.MyApp"</subsystem>
-->
<category>"Interval"</category>
<name>?name</name>
<pattern>
<message>"Label:" ?label ",Concept:" ?concept</message>
</pattern>
<column>
<mnemonic>name</mnemonic>
<title>Name</title>
<type>string</type>
<expression>?name</expression>
</column>
<column>
<mnemonic>label</mnemonic>
<title>Label</title>
<type>string</type>
<expression>?label</expression>
</column>
<column>
<mnemonic>concept</mnemonic>
<title>Concept</title>
<type>event-concept</type>
<expression>?concept</expression>
</column>
</os-signpost-point-schema>
<os-signpost-interval-schema>
<id>custom-interval-schema</id>
<title>Intervals</title>
<owner>
<name>Robert Ryan</name>
</owner>
<purpose>Provide mechanism for multicolored intervals posted by `os_signpost`; The string generated by `os_signpost` must be in form of "Label:%d,Concept:%{public}#", where "Label" is string that will control what text appears in the interval, and "Concept" is one of the strings listed in https://help.apple.com/instruments/developer/mac/current/#/dev66257045 that dictates the color of the interval. No spaces after the commas within this string.</purpose>
<note>That message must use that printf-style format, not embedding the values in the format string literal.</note>
<!-- you can constrain this to a particular subsystem if you'd like:
<subsystem>"com.domain.MyApp"</subsystem>
-->
<category>"Interval"</category>
<name>?name</name>
<start-pattern>
<message>"Label:" ?label ",Concept:" ?concept</message>
</start-pattern>
<column>
<mnemonic>name</mnemonic>
<title>Name</title>
<type>string</type>
<expression>?name</expression>
</column>
<column>
<mnemonic>label</mnemonic>
<title>Label</title>
<type>string</type>
<expression>?label</expression>
</column>
<column>
<mnemonic>concept</mnemonic>
<title>Concept</title>
<type>event-concept</type>
<expression>?concept</expression>
</column>
</os-signpost-interval-schema>
<instrument>
<id>com.robertmryan.CustomInterval.instrument</id>
<title>Custom Points of Interest</title>
<category>Behavior</category>
<purpose>Provide multi-colored intervals as dictated by the "event-concept" parsed from the `start-pattern` string.</purpose>
<icon>Generic</icon>
<limitations></limitations>
<create-table>
<id>custom-interval-table</id>
<schema-ref>custom-interval-schema</schema-ref>
</create-table>
<create-table>
<id>custom-point-table</id>
<schema-ref>custom-point-schema</schema-ref>
</create-table>
<graph>
<title>Custom Interval Graph</title>
<lane>
<title>Points</title>
<table-ref>custom-point-table</table-ref>
<plot-template>
<instance-by>name</instance-by>
<label-format>%s</label-format>
<value-from>name</value-from>
<color-from>concept</color-from>
<label-from>label</label-from>
</plot-template>
</lane>
<lane>
<title>Intervals</title>
<table-ref>custom-interval-table</table-ref>
<plot-template>
<instance-by>name</instance-by>
<label-format>%s</label-format>
<value-from>name</value-from>
<color-from>concept</color-from>
<label-from>label</label-from>
<qualified-by>layout-qualifier</qualified-by>
</plot-template>
</lane>
</graph>
<list>
<title>Custom Regions of Interest</title>
<table-ref>custom-interval-table</table-ref>
<column>name</column>
<column>label</column>
<column>concept</column>
<column>start</column>
<column>duration</column>
</list>
<list>
<title>Custom Points of Interest</title>
<table-ref>custom-point-table</table-ref>
<column>name</column>
<column>label</column>
<column>concept</column>
</list>
</instrument>
</package>

Answer 1

I posted this on the Apple forums, too, and received this answer:
… To customize the icon that is set in the point rendering scenario, your type that is selected in your value-from field needs to have a "Special Value Treatment" defined. In your case, instead of using name, you could safely use event-concept.
The mapping between Value -> (Icon, Color) can be found in the etype documentation. For event concept, that would be: https://help.apple.com/instruments/developer/mac/current/#/dev66257045
Please let me know if that helps!
Kacper
Posted 57 minutes ago by kacperh_ 
In short, the event-concept can control both the color and the symbol for the event, too.
So, I replaced the value-from in the points lane to use the parsed event-concept string, just like the color-from was doing:
<lane>
<title>Points</title>
<table-ref>custom-point-table</table-ref>
<plot-template>
<instance-by>name</instance-by>
<label-format>%s</label-format>
<value-from>concept</value-from>
<color-from>concept</color-from>
<label-from>label</label-from>
</plot-template>
</lane>
And that yielded: