Incremental and Decremental Energy Offer Curves (IDO)

Retired — no longer supported

Incremental and Decremental Energy Offer Curves (IDO) were removed with the RTC+B implementation on 12/05/2025. ERCOT no longer accepts or returns this message, and IncDecOffer is no longer a valid element of BidSet.

This page is retained for reference when interpreting submissions made before that date. The structure diagram, field tables and XML examples below describe the pre-RTC+B schema and will not validate against the current ERCOT Web Services XSDs.

The following diagram describes the structure of Incremental and Decremental Energy Offer Curves. This shows the details of the FipFop and PriceCurve structures that are contained within:

Incremental and Decremental Energy Offer Curve Structure

Both the IncrementalCurve and DecrementalCurve use the PriceCurve structure as described previously in this document, but only one (either an IncrementalCurve or a DecrementalCurve) can be specified per each IncDecOffer. On submission, the following table describes the items used for an IncDecOffer:

Element Req? Datatype Description Values
startTime N dateTime Start time for bid Valid start hour boundary for trade date
endTime N dateTime End time for bid Valid end hour boundary for trade date
externalId N string External ID QSE supplied
resource K string Resource Valid resource name
combinedCycle N string Combined cycle to which resource is associated Not required. Value ignored if provided.
expirationTime Y dateTime Offer expiration time Valid time before or during the trade date
FipFop/fipPercent Y decimal Fuel index price percent >= 0, <= 100
FipFop/fopPercent Y decimal Fuel oil price percent >= 0, <= 100
IncrementalCurve/startTime

If INC

offer

 dateTime Start time for curve Valid hour boundary
IncrementalCurve/endTime

If INC

offer

 dateTime End time for curve Valid hour boundary
IncrementalCurve/curveStyle

If INC

offer

 string Type of curve CURVE
IncrementalCurve/CurveData/xvalue

If INC

offer

 float Megawatts Quantity in MW
IncrementalCurve/CurveData/y1value

If INC

offer

 float $/MWh Incremental price in $/MWh, must be greater than corresponding Decremental curve value
DecrementalCurve/startTime If DEC offer dateTime Start time for curve Valid hour boundary
DecrementalCurve/endTime If DEC offer dateTime End time for curve Valid hour boundary
DecrementalCurve/curveStyle If DEC offer string Type of curve CURVE
DecrementalCurve/CurveData/xvalue If DEC offer float Megawatts Quantity in MW
DecrementalCurve/CurveData/y1value If DEC offer float $/MWh Decremental price in $/MWh, must be less than corresponding incremental curve value

The following is an XML example for an IncDecOffer (In this case, a Decremental Curve)

<BidSet xmlns="http://www.ercot.com/schema/2007-06/nodal/ews" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.ercot.com/schema/2007-06/nodal/ews ErcotTransactions.xsd">
    <tradingDate>2008-01-01</tradingDate>
    <IncDecOffer>
        <startTime>2008-01-01T00:00:00-05:00</startTime>
        <endTime>2008-01-02T00:00:00-05:00</endTime>
        <marketType>DAM</marketType>
        <expirationTime>2008-01-02T00:00:00-05:00</expirationTime>
        <resource>Resource123</resource>
        <FipFop>
            <startTime>2008-01-01T00:00:00-05:00</startTime>
            <endTime>2008-01-02T00:00:00-05:00</endTime>
            <fipPercent>25</fipPercent>
            <fopPercent>75</fopPercent>
        </FipFop>
        <DecrementalCurve>
            <startTime>2008-01-01T00:00:00-05:00</startTime>
            <endTime>2008-01-02T00:00:00-05:00</endTime>
            <curveStyle>FIXED</curveStyle>
            <CurveData>
                <!--The price value in the pq_curve element of DEC Offer must be less than the existing INC offer price-->
                <xvalue>2.14</xvalue>
                <y1value>2.14</y1value>
            </CurveData>
            <reason>OUT</reason>
        </DecrementalCurve>
    </IncDecOffer>
</BidSet>

And the corresponding response:

<ns1:BidSet xmlns:ns1="http://www.ercot.com/schema/2007-06/nodal/ews">
    <ns1:tradingDate>2008-06-15</ns1:tradingDate>
    <ns1:IncDecOffer>
        <ns1:mRID>QSAMP.20080615.IDO.Resource1.DEC</ns1:mRID>
        <ns1:externalId/>
        <ns1:status>ACCEPTED</ns1:status>
        <ns1:error>
            <ns1:severity>INFORMATIVE</ns1:severity>
            <ns1:text>Successfully processed the ERCOT Inc Dec Offer.</ns1:text>
        </ns1:error>
    </ns1:IncDecOffer>
</ns1:BidSet>