Inheritance principle: clarify the procedure of which files would be considered

[yarikoptic]

It might be just me, but from current wording it is not 100% clear if it is only _run and _rec are of special treatment to be "generalized over" or any other possible key/value pair (_acq etc). I.e. for a file

sub-<label>/[ses-<label>/]
    func/
        sub-<label>[_ses-<label>]_task-<label>[_acq-<label>][_ce-<label>][_dir-<label>][_rec-<label>][_run-<index>][_echo-<index>]_<contrast_label>.json

would task-<label>_<contrast_label>.json at the top level be considered, disregarding any possibly present OPTIONAL key (like _acq, _ce, etc)?

What about anatomy, e.g. for a file

sub-<label>/[ses-<label>/]
    anat/
        sub-<label>[_ses-<label>][_acq-<label>][_ce-<label>][_rec-<label>][_run-<index>]_<suffix>.json

would <suffix>.json be considered regardless any of the possible acq, ce etc present in the target subject/session specific file?

To make it totally clear, it might be worth to formulate explicitly a generic rule to generate "higher level" filename considered for inheritance for any given "leaf" file (might be already as implemented in pybids -- didn't check yet):

• strip sub-<label>_ prefix while providing generalization across subject(s)
• remove _ses-<label> while providing generalization across session(s)
• remove any _key-<value> if generalizing across various types of acquisition
• strip possibly present leading _ if left only with the suffix, such as _<suffix>.json in anat example

what do you think? Or it is just me, and current wording is sufficient (I would be ok with that)

FWIW, here is a list (click to expand) of all interesting "corner cases" across openneuro datasets

$> ls -l */*json | grep -v -e dataset_de -e participa -e task-  
-rw------- 1 yoh yoh   240 Dec  4 15:36 ds000101/T1w.json
-rw------- 1 yoh yoh   247 Dec  4 15:37 ds000102/T1w.json
-rw------- 1 yoh yoh  1372 Dec  4 16:08 ds000117/acq-mprage_T1w.json
-rw------- 1 yoh yoh    82 Dec  4 16:08 ds000117/run-1_echo-1_FLASH.json
-rw------- 1 yoh yoh    82 Dec  4 16:08 ds000117/run-1_echo-2_FLASH.json
-rw------- 1 yoh yoh    82 Dec  4 16:08 ds000117/run-1_echo-3_FLASH.json
-rw------- 1 yoh yoh    82 Dec  4 16:08 ds000117/run-1_echo-4_FLASH.json
-rw------- 1 yoh yoh    82 Dec  4 16:08 ds000117/run-1_echo-5_FLASH.json
-rw------- 1 yoh yoh    82 Dec  4 16:08 ds000117/run-1_echo-6_FLASH.json
-rw------- 1 yoh yoh    82 Dec  4 16:08 ds000117/run-1_echo-7_FLASH.json
-rw------- 1 yoh yoh    83 Dec  4 16:08 ds000117/run-2_echo-1_FLASH.json
-rw------- 1 yoh yoh    83 Dec  4 16:08 ds000117/run-2_echo-2_FLASH.json
-rw------- 1 yoh yoh    83 Dec  4 16:08 ds000117/run-2_echo-3_FLASH.json
-rw------- 1 yoh yoh    83 Dec  4 16:08 ds000117/run-2_echo-4_FLASH.json
-rw------- 1 yoh yoh    83 Dec  4 16:08 ds000117/run-2_echo-5_FLASH.json
-rw------- 1 yoh yoh    83 Dec  4 16:08 ds000117/run-2_echo-6_FLASH.json
-rw------- 1 yoh yoh    83 Dec  4 16:08 ds000117/run-2_echo-7_FLASH.json
-rw------- 1 yoh yoh   146 Dec  4 15:46 ds000144/T1w.json
-rw------- 1 yoh yoh   128 Dec  4 15:47 ds000164/T1w.json
-rw------- 1 yoh yoh   204 Dec  4 15:46 ds000168/T1w.json
-rw------- 1 yoh yoh   288 Dec  4 15:42 ds000174/T1w.json
-rw------- 1 yoh yoh  1184 Dec  4 15:58 ds000201/T1w.json
-rw------- 1 yoh yoh  1127 Dec  4 15:58 ds000201/T2w.json
-rw------- 1 yoh yoh   901 Dec  4 15:59 ds000201/dwi.json
-rw------- 1 yoh yoh   209 Dec  4 15:47 ds000205/T1w.json
-rw------- 1 yoh yoh   207 Dec  4 15:41 ds000208/T1w.json
-rw------- 1 yoh yoh   141 Dec  4 15:49 ds000213/T1w.json
-rw------- 1 yoh yoh   169 Dec  4 15:48 ds000214/T1w.json
-rw------- 1 yoh yoh   226 Dec  4 15:48 ds000222/T1w.json
-rw------- 1 yoh yoh    62 Dec  4 15:48 ds000229/T1w.json
-rw------- 1 yoh yoh   285 Dec  4 15:44 ds000231/T1w.json
-rw------- 1 yoh yoh   408 Dec  4 15:49 ds000239/T1w.json
-rw------- 1 yoh yoh   217 Dec  4 15:44 ds000240/T1w.json
-rw------- 1 yoh yoh    73 Dec  4 16:05 ds000244/dir-0_epi.json
-rw------- 1 yoh yoh    74 Dec  4 16:05 ds000244/dir-1_epi.json
-rw------- 1 yoh yoh   197 Dec  4 16:05 ds000244/dwi.json
-rw------- 1 yoh yoh   252 Dec  4 15:47 ds000245/T1w.json
-rw------- 1 yoh yoh   195 Dec  4 15:42 ds000248/acq-epi_T1w.json
-rw------- 1 yoh yoh    77 Dec  4 15:42 ds000248/acq-flipangle05_run-01_MEFLASH.json
-rw------- 1 yoh yoh    78 Dec  4 15:42 ds000248/acq-flipangle30_run-01_MEFLASH.json
-rw------- 1 yoh yoh   144 Dec  4 15:48 ds000254/T1w.json
-rw------- 1 yoh yoh   176 Dec  4 15:43 ds000255/T1w.json
-rw------- 1 yoh yoh   215 Dec  4 15:55 ds001021/T1w.json
-rw------- 1 yoh yoh   157 Dec  4 15:55 ds001021/dwi.json
-rw------- 1 yoh yoh    54 Dec  4 15:55 ds001021/phasediff.json
-rw------- 1 yoh yoh    69 Dec  4 15:39 ds001105/dir-AP_epi.json
-rw------- 1 yoh yoh    68 Dec  4 15:39 ds001105/dir-PA_epi.json
-rw------- 1 yoh yoh   259 Dec  4 16:01 ds001246/T1w.json
-rw------- 1 yoh yoh   253 Dec  4 16:01 ds001246/inplaneT2.json
-rw------- 1 yoh yoh   977 Dec  4 15:52 ds001386/bold.json
-rw------- 1 yoh yoh    75 Dec  4 15:57 ds001454/phasediff.json
-rw------- 1 yoh yoh   376 Dec  4 16:04 ds001486/T1w.json
-rw------- 1 yoh yoh   247 Dec  4 16:07 ds001525/T1w.json
-rw------- 1 yoh yoh    75 Dec  4 16:09 ds001545/phasediff.json
-rw------- 1 yoh yoh   517 Dec  4 16:16 ds001597/T1w.json
-rw------- 1 yoh yoh   517 Dec  4 16:16 ds001597/T2w.json

A list (click to expand) of all interesting task- "corner cases" where it is not just task-_bold.json across openneuro datasets

$> ls -l */*json | grep -v -e dataset_de -e participa | grep task-.*_[^b]
-rw------- 1 yoh yoh   284 Dec  4 15:47 ds000164/task-stroop_events.json
-rw------- 1 yoh yoh    76 Dec  4 15:59 ds000201/task-hands_physio.json
-rw------- 1 yoh yoh   596 Dec  4 15:48 ds000214/task-Cyberball_events.json
-rw------- 1 yoh yoh   884 Dec  4 15:46 ds000234/task-motorphotic_asl.json
-rw------- 1 yoh yoh   786 Dec  4 15:44 ds000235/task-rest_asl.json
-rw------- 1 yoh yoh   786 Dec  4 15:42 ds000236/task-rest_asl.json
-rw------- 1 yoh yoh   224 Dec  4 15:47 ds000237/task-MemorySpan_acq-multiband_bold.json
-rw------- 1 yoh yoh   934 Dec  4 15:44 ds000240/task-restEyesOpen_asl.json
-rw------- 1 yoh yoh  1628 Dec  4 16:05 ds000244/task-ArchiEmotional_acq-ap_bold.json
-rw------- 1 yoh yoh  1628 Dec  4 16:05 ds000244/task-ArchiEmotional_acq-ap_sbref.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ArchiEmotional_acq-pa_bold.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ArchiEmotional_acq-pa_sbref.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-ArchiSocial_acq-ap_bold.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-ArchiSocial_acq-ap_sbref.json
-rw------- 1 yoh yoh  1624 Dec  4 16:05 ds000244/task-ArchiSocial_acq-pa_bold.json
-rw------- 1 yoh yoh  1624 Dec  4 16:05 ds000244/task-ArchiSocial_acq-pa_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ArchiSpatial_acq-ap_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ArchiSpatial_acq-ap_sbref.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-ArchiSpatial_acq-pa_bold.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-ArchiSpatial_acq-pa_sbref.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ArchiStandard_acq-ap_bold.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ArchiStandard_acq-ap_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ArchiStandard_acq-pa_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ArchiStandard_acq-pa_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn01_acq-pa_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn01_acq-pa_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn02_acq-pa_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn02_acq-pa_sbref.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsTrn03_acq-ap_bold.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsTrn03_acq-ap_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn04_acq-pa_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn04_acq-pa_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn05_acq-pa_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn05_acq-pa_sbref.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsTrn06_acq-ap_bold.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsTrn06_acq-ap_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn07_acq-pa_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn07_acq-pa_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn08_acq-pa_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn08_acq-pa_sbref.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsTrn09_acq-ap_bold.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsTrn09_acq-ap_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn10_acq-pa_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn10_acq-pa_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn11_acq-pa_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsTrn11_acq-pa_sbref.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsTrn12_acq-ap_bold.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsTrn12_acq-ap_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsVal01_acq-pa_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsVal01_acq-pa_sbref.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsVal02_acq-ap_bold.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsVal02_acq-ap_sbref.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsVal03_acq-ap_bold.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsVal03_acq-ap_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsVal04_acq-pa_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsVal04_acq-pa_sbref.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsVal05_acq-ap_bold.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsVal05_acq-ap_sbref.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsVal06_acq-ap_bold.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsVal06_acq-ap_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsVal07_acq-pa_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-ClipsVal07_acq-pa_sbref.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsVal08_acq-ap_bold.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsVal08_acq-ap_sbref.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsVal09_acq-ap_bold.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-ClipsVal09_acq-ap_sbref.json
-rw------- 1 yoh yoh  1623 Dec  4 16:05 ds000244/task-ContRing_acq-ap_bold.json
-rw------- 1 yoh yoh  1623 Dec  4 16:05 ds000244/task-ContRing_acq-ap_sbref.json
-rw------- 1 yoh yoh  1622 Dec  4 16:05 ds000244/task-ExpRing_acq-pa_bold.json
-rw------- 1 yoh yoh  1622 Dec  4 16:05 ds000244/task-ExpRing_acq-pa_sbref.json
-rw------- 1 yoh yoh  1624 Dec  4 16:05 ds000244/task-HcpEmotion_acq-ap_bold.json
-rw------- 1 yoh yoh  1624 Dec  4 16:05 ds000244/task-HcpEmotion_acq-ap_sbref.json
-rw------- 1 yoh yoh  1623 Dec  4 16:05 ds000244/task-HcpEmotion_acq-pa_bold.json
-rw------- 1 yoh yoh  1623 Dec  4 16:05 ds000244/task-HcpEmotion_acq-pa_sbref.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-HcpGambling_acq-ap_bold.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-HcpGambling_acq-ap_sbref.json
-rw------- 1 yoh yoh  1624 Dec  4 16:05 ds000244/task-HcpGambling_acq-pa_bold.json
-rw------- 1 yoh yoh  1624 Dec  4 16:05 ds000244/task-HcpGambling_acq-pa_sbref.json
-rw------- 1 yoh yoh  1624 Dec  4 16:05 ds000244/task-HcpLanguage_acq-ap_bold.json
-rw------- 1 yoh yoh  1624 Dec  4 16:05 ds000244/task-HcpLanguage_acq-ap_sbref.json
-rw------- 1 yoh yoh  1623 Dec  4 16:05 ds000244/task-HcpLanguage_acq-pa_bold.json
-rw------- 1 yoh yoh  1623 Dec  4 16:05 ds000244/task-HcpLanguage_acq-pa_sbref.json
-rw------- 1 yoh yoh  1622 Dec  4 16:05 ds000244/task-HcpMotor_acq-ap_bold.json
-rw------- 1 yoh yoh  1622 Dec  4 16:05 ds000244/task-HcpMotor_acq-ap_sbref.json
-rw------- 1 yoh yoh  1621 Dec  4 16:05 ds000244/task-HcpMotor_acq-pa_bold.json
-rw------- 1 yoh yoh  1621 Dec  4 16:05 ds000244/task-HcpMotor_acq-pa_sbref.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-HcpRelational_acq-ap_bold.json
-rw------- 1 yoh yoh  1627 Dec  4 16:05 ds000244/task-HcpRelational_acq-ap_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-HcpRelational_acq-pa_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-HcpRelational_acq-pa_sbref.json
-rw------- 1 yoh yoh  1623 Dec  4 16:05 ds000244/task-HcpSocial_acq-ap_bold.json
-rw------- 1 yoh yoh  1623 Dec  4 16:05 ds000244/task-HcpSocial_acq-ap_sbref.json
-rw------- 1 yoh yoh  1622 Dec  4 16:05 ds000244/task-HcpSocial_acq-pa_bold.json
-rw------- 1 yoh yoh  1622 Dec  4 16:05 ds000244/task-HcpSocial_acq-pa_sbref.json
-rw------- 1 yoh yoh  1619 Dec  4 16:05 ds000244/task-HcpWm_acq-ap_bold.json
-rw------- 1 yoh yoh  1619 Dec  4 16:05 ds000244/task-HcpWm_acq-ap_sbref.json
-rw------- 1 yoh yoh  1618 Dec  4 16:05 ds000244/task-HcpWm_acq-pa_bold.json
-rw------- 1 yoh yoh  1618 Dec  4 16:05 ds000244/task-HcpWm_acq-pa_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-RSVPLanguage00_acq-ap_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-RSVPLanguage00_acq-ap_sbref.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-RSVPLanguage00_acq-pa_bold.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-RSVPLanguage00_acq-pa_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-RSVPLanguage01_acq-ap_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-RSVPLanguage01_acq-ap_sbref.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-RSVPLanguage01_acq-pa_bold.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-RSVPLanguage01_acq-pa_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-RSVPLanguage02_acq-ap_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-RSVPLanguage02_acq-ap_sbref.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-RSVPLanguage02_acq-pa_bold.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-RSVPLanguage02_acq-pa_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-RSVPLanguage03_acq-ap_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-RSVPLanguage03_acq-ap_sbref.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-RSVPLanguage03_acq-pa_bold.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-RSVPLanguage03_acq-pa_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-RSVPLanguage04_acq-ap_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-RSVPLanguage04_acq-ap_sbref.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-RSVPLanguage04_acq-pa_bold.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-RSVPLanguage04_acq-pa_sbref.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-RSVPLanguage05_acq-ap_bold.json
-rw------- 1 yoh yoh  1626 Dec  4 16:05 ds000244/task-RSVPLanguage05_acq-ap_sbref.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-RSVPLanguage05_acq-pa_bold.json
-rw------- 1 yoh yoh  1625 Dec  4 16:05 ds000244/task-RSVPLanguage05_acq-pa_sbref.json
-rw------- 1 yoh yoh  1623 Dec  4 16:05 ds000244/task-WedgeAnti_acq-ap_bold.json
-rw------- 1 yoh yoh  1623 Dec  4 16:05 ds000244/task-WedgeAnti_acq-ap_sbref.json
-rw------- 1 yoh yoh  1622 Dec  4 16:05 ds000244/task-WedgeAnti_acq-pa_bold.json
-rw------- 1 yoh yoh  1622 Dec  4 16:05 ds000244/task-WedgeAnti_acq-pa_sbref.json
-rw------- 1 yoh yoh  1623 Dec  4 16:05 ds000244/task-WedgeClock_acq-ap_bold.json
-rw------- 1 yoh yoh  1623 Dec  4 16:05 ds000244/task-WedgeClock_acq-ap_sbref.json
-rw------- 1 yoh yoh  1622 Dec  4 16:05 ds000244/task-WedgeClock_acq-pa_bold.json
-rw------- 1 yoh yoh  1622 Dec  4 16:05 ds000244/task-WedgeClock_acq-pa_sbref.json
-rw------- 1 yoh yoh   843 Dec  4 15:48 ds000254/task-bilateralfingertapping_echo-1_bold.json
-rw------- 1 yoh yoh   842 Dec  4 15:48 ds000254/task-bilateralfingertapping_echo-2_bold.json
-rw------- 1 yoh yoh   843 Dec  4 15:48 ds000254/task-bilateralfingertapping_echo-3_bold.json
-rw------- 1 yoh yoh   843 Dec  4 15:48 ds000254/task-bilateralfingertapping_echo-4_bold.json
-rw------- 1 yoh yoh  2345 Dec  4 15:55 ds001021/task-BREATHHOLD_acq-1400_bold.json
-rw------- 1 yoh yoh  1916 Dec  4 15:55 ds001021/task-CHECKERBOARD_acq-1400_bold.json
-rw------- 1 yoh yoh  1605 Dec  4 15:55 ds001021/task-CHECKERBOARD_acq-645_bold.json
-rw------- 1 yoh yoh  1593 Dec  4 15:55 ds001021/task-rest_acq-1400_bold.json
-rw------- 1 yoh yoh  1314 Dec  4 15:55 ds001021/task-rest_acq-645_bold.json
-rw------- 1 yoh yoh  1134 Dec  4 15:55 ds001021/task-rest_acq-CAP_bold.json
-rw------- 1 yoh yoh    76 Dec  4 16:11 ds001553/task-checkerboard_events.json
-rw------- 1 yoh yoh   869 Dec  4 16:16 ds001597/task-cuedMFM_events.json
-rw------- 1 yoh yoh    25 Dec  4 16:18 ds001600/task-rest_acq-AP_bold.json
-rw------- 1 yoh yoh    25 Dec  4 16:18 ds001600/task-rest_acq-PA_bold.json
-rw------- 1 yoh yoh    25 Dec  4 16:18 ds001600/task-rest_acq-v1_bold.json
-rw------- 1 yoh yoh    25 Dec  4 16:18 ds001600/task-rest_acq-v2_bold.json
-rw------- 1 yoh yoh    25 Dec  4 16:18 ds001600/task-rest_acq-v4_bold.json

edit 1: "The constraint"
another not entirely clear aspect to me, which is the not spelled out, is the requirement to have only a single "applicable" file at any given level, which is demonstrated in Example 1: Two JSON files at same level that are applicable for NIfTI file.:

"violating the constraint that no more than one file may be defined at a given level of the directory structure"
(wording around soon to be tuned up a bit in a https://github.com/bids-standard/bids-specification/pull/98/files#diff-ba564f153b960d803d493fe37fbbb34eL148). I do not see a clear definition of such constraint in the actual text describing inheritance principle. While working on fixing auto aggregation of common fields into the top level files to be inherited within heudiconv I placed myself into a corner with an example of having e.g.

• sub-1_task-task1_run-1_bold.json and
• sub-1_task-task1_acq-X_run-1_bold.json

per subject (should be ok), and then trying to aggregate over them while retaining also _acq- if defined. Then I would end up with

• task-task1_bold.json
• task-task1_acq-X_bold.json

at the top level. Is this legit???
Should then _acq-X_bold leaf files inherit also from task-task1_bold.json? It shouldn't be so I guess.
And it is not just a matter of having that constraint "no more than one file may be defined at a given level of the directory structure", because I could potentially place the _acq-X in per-subject directory, thus avoiding it. It is a matter of clear definition on how we "expand" the common filename to match any leaf one. If it is a matter of the fact that we could expand into a leaf file with arbitrary additional _key-value pairs, then the situation above could be "Ok" so that task-task1_acq-X_bold.json could extend (or overwrite, but not delete) fields defined in task-task1_bold.json.

[yarikoptic]

and only now realized that we do not "officially/clearly" have a way to define the most common .json for inheritance, which might generalize for ALL other files.
Well -- dataset_description.json is kinda like that file -- since I guess all information pertinent to the dataset as a whole is pertinent to individual files as well. But then should it be considered while constructing the full metadata record for a particular leaf file?

[yarikoptic]

Thinking about it even more, I still like my algorithmic approach (with a single caveat outlined in the bottom of the original post, still thinking about it) to the definition and would like to propose to remove that restriction to have only a single "applicable" file at any given level.

1. as stated above, the most common file to absorb all "common" fields is actually already there and it is dataset_description.json. Whatever applies to the entire dataset does apply to each file by default IMHO.
2. I might want to have ses-X.json on top level to provide specific common fields for any subject/modality for ses-X in the study (e.g. that a specific scanner/software was used - a real use case from today!), which was different from another scanner in ses-Y.
3. And then I would like to have task-A_bold.json and task-B_bold.json which would have other common fields specific to each task so I could have a quick overview of differences between tasks.
   I could furthermore provide specifications for different acq- etc, pretty much may be even per each _key- if I am that good. That makes it possible to scale nicely for large(r) studies and provide a nice summary of differences on top of the dataset.

In above example, all 3 specific types of .json files (or at least two, if we exclude dataset_description.json) at the same top level should then be used while "inheriting".
Instead of the rule for "a single applicable file" there could be a rule (with a validator check) that files at any given level must not be in conflict, in that they must not re-define the same field (i.e. a field F to be defined both in task-_bold.json and ses-.json files) thus making it ambiguous since would depend on the order on how "inheritance" is done across those files at the same level. If there is no overlap in fields, no ambiguity -- no need for a restriction.

[yarikoptic]

Continuing talking to myself, here is a list of non task- files in the top level to be inherited:

$> ls ds00*/*json | grep -v -e dataset_description -e participants -e task- | xargs -n 1 basename | sort | uniq -c                                                                
      1 acq-epi_T1w.json
      1 acq-flipangle05_run-01_MEFLASH.json
      1 acq-flipangle30_run-01_MEFLASH.json
      1 acq-moldOFF_T1w.json
      1 acq-moldON_T1w.json
      1 acq-mprage_T1w.json
      1 bold.json
      1 dir-0_epi.json
      1 dir-1_epi.json
      1 dir-AP_epi.json
      1 dir-PA_epi.json
      3 dwi.json
      1 inplaneT2.json
      3 phasediff.json
      1 run-1_echo-1_FLASH.json
      1 run-1_echo-2_FLASH.json
      1 run-1_echo-3_FLASH.json
      1 run-1_echo-4_FLASH.json
      1 run-1_echo-5_FLASH.json
      1 run-1_echo-6_FLASH.json
      1 run-1_echo-7_FLASH.json
      1 run-2_echo-1_FLASH.json
      1 run-2_echo-2_FLASH.json
      1 run-2_echo-3_FLASH.json
      1 run-2_echo-4_FLASH.json
      1 run-2_echo-5_FLASH.json
      1 run-2_echo-6_FLASH.json
      1 run-2_echo-7_FLASH.json
     24 T1w.json
      2 T2w.json

attn @tyarkoni (happen you didn't spot my whining here before)

[yarikoptic]

wow -- it is very popular in back references, but nobody voiced their opinions. @tsalo @sappelhoff @Remi-Gau @effigies WDYT?