There is no guidance on mapping medication frequency (the effectiveTime[@operator='A'] element in CDA). This is a key part of discrete medications and needs to be handled when converting CDA to FHIR.

Not to design the entire thing here, but some things it needs to address:

• EIVL_TS times need to populate `when` and `offset` (or possibly dayOfWeek and timeOfDay)
• PIVL_TS should populate frequency/period/periodUnit (and potentially frequencyMax / periodMax if a range is given) depending on value and @institutionSpecified

This is another area where additional intelligence beyond a table-map is needed, since there can be different interpretations depending on the value.

The C-CDA examples task force put together a list of common frequencies that shows different variations that mean the same thing. Often times the value in CDA may be a decimal, but if it corresponds to a FHIR period, then it must be converted to a different unit.

For example, bid could be represented as 0.5 d or 12 h (with institutionSpecified=true), but both should be converted to a FHIR timing of frequency: 2, periodUnit = day.

Meanwhile if institutionSpecified = false, that frequency (aka Q12H) should be represented as frequency: 1, period: 12, periodUnit = hour.