What metadata fields do we want to request for the specification

[KirstieJane]

I have such a list from the last time I dived into the code:

FieldnamesOriginal  FieldnamesBIDS                  Scaling
RepetitionTime          ExcitationRepetitionTime    1
EchoTime            EchoTime                    1
FlipAngle           FlipAngle                   1
B1mapNominalFAValues    B1mapNominalFAValues            1
B1mapMixingTime         MixingTime                  1
epiReadoutDuration  epiReadoutDuration          1
PhaseEncodingDirectionSign  PhaseEncodingDirectionSign  NaN
ScanningSequence    ScanningSequence            NaN
SequenceName            SequenceName                    NaN
ProtocolName            ProtocolName                    NaN
RFSpoilingPhaseIncrement    RFSpoilingPhaseIncrement    1
spoilingGradientMoment  spoilingGradientMoment         1
spoilingGradientDuration    spoilingGradientDuration    1

These are a bit outdated but can be easily updated, such that the DICOM-to-NIFTI conversion produces the right BIDS-fields. Then variable names can easily be updated in the main code, as number crunching routines typically use shorter names and simply 'import' the required parameters at the beginning.

[KirstieJane]

There are some already in this version (thanks @agahkarakuzu)

I think this needs to be added to the ProposedChangesToSpecification.md file.

And maybe @christophephillips can review the changes and see if there are any others we need to add.

[KirstieJane]

This is related to #56.

[agahkarakuzu]

Please see 69f8d5857ca8288deea5cbad78fbe513243c2f2b for the additions I made for metadata.