This code system http://hl7.org/fhir/guidance-module-code defines the following codes:

CodeDisplayDefinition
bmi-calculator BMI CalculatorA Body Mass Index (BMI) calculator.
mme-calculator MME CalculatorA Morphine Milligram Equivalent (MME) calculator.
opioid-cds Opioid CDSClinical Decision Support for Opioid Prescribing.
anc-cds ANC CDSClinical Decision Support for Antenatal Care.
chf-pathway CHF PathwayCongestive Heart Failure Pathway
covid-19-severity COVID-19 Severity ScoreA COVID-19 Severity Score Calculator.
<status value="active"/><experimental value="true"/><date value="2021-01-05T10:01:24+11:00"/><publisher value="HL7 (FHIR Project)"/><contact><telecom><system value="url"/><value value="http://hl7.org/fhir"/></telecom><telecom><system value="email"/><value value="fhir@lists.hl7.org"/></telecom></contact><description value="Example guidance module codes."/><jurisdiction><coding><system value="http://unstats.un.org/unsd/methods/m49/m49.htm"/><code value="001"/><display value="World"/></coding></jurisdiction><caseSensitive value="true"/><valueSet value="http://hl7.org/fhir/ValueSet/guidance-module-code"/><content value="complete"/><concept><code value="bmi-calculator"/><display value="BMI Calculator"/><definition value="A Body Mass Index (BMI) calculator."/></concept><concept><code value="mme-calculator"/><display value="MME Calculator"/><definition value="A Morphine Milligram Equivalent (MME) calculator."/></concept><concept><code value="opioid-cds"/><display value="Opioid CDS"/><definition value="Clinical Decision Support for Opioid Prescribing."/></concept><concept><code value="anc-cds"/><display value="ANC CDS"/><definition value="Clinical Decision Support for Antenatal Care."/></concept><concept><code value="chf-pathway"/><display value="CHF Pathway"/><definition value="Congestive Heart Failure Pathway"/></concept><concept><code value="covid-19-severity"/><display value="COVID-19 Severity Score"/><definition value="A COVID-19 Severity Score Calculator."/></concept></CodeSystem>