Making blocks optional and conditional entry where there is no header name - json

Question

I am trying to write a json schema to import a csv file. A simplified version of the file is:
000,OUTCOME,111,20220320,FT
001,A.Name1,,,A,
002,A.Name2,,20220101,C,
999,2
000 is a header block
001 & 002 are the body and can have multiple instances. Structurally they are the same
999 is the trailer
the schema I have is
{
"conf_name": "FileTest",
"has_blocks": true,
"has_headers": false,
"enabled_extensions": [
{
"extension": "csv",
"delimiter": ","
}
],
"file_type": "FileTest",
"columns": [
{
"blockName": "000",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "M",
"type": "text",
"format": "",
"values": [
"OUTCOME"
],
"conditional": ""
}
},
{
"blockName": "000",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "M",
"type": "int",
"format": "",
"values": "",
"conditional": ""
}
},
{
"blockName": "000",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "M",
"type": "date",
"format": "yyyyMMdd",
"values": "",
"conditional": ""
}
},
{
"blockName": "000",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "M",
"type": "text",
"format": "",
"values": "",
"conditional": ""
}
},
{
"blockName": "001",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "M",
"type": "text",
"format": "",
"values": "",
"conditional": ""
}
},
{
"blockName": "001",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "O",
"type": "text",
"format": "",
"values": "",
"conditional": ""
}
},
{
"blockName": "001",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "C",
"type": "date",
"format": "yyyyMMdd",
"values": "",
"conditional": {
"columnName": "Column5",
"operation": "==C THEN NOTEMPTY",
"value": ""
}
}
},
{
"blockName": "001",
"name": "Column5",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "M",
"type": "text",
"format": "",
"values": [
"A",
"B",
"C"
],
"conditional": ""
}
},
{
"blockName": "001",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "O",
"type": "text",
"format": "",
"values": [
"Y",
"N"
],
"conditional": ""
}
},
{
"blockName": "002",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "M",
"type": "text",
"format": "",
"values": "",
"conditional": ""
}
},
{
"blockName": "002",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "O",
"type": "text",
"format": "",
"values": "",
"conditional": ""
}
},
{
"blockName": "002",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "C",
"type": "date",
"format": "yyyyMMdd",
"values": "",
"conditional": {
"columnName": "Column5",
"operation": "==C THEN NOTEMPTY",
"value": ""
}
}
},
{
"blockName": "002",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "M",
"type": "text",
"format": "",
"values": [
"A",
"B",
"C"
],
"conditional": ""
}
},
{
"blockName": "002",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "O",
"type": "text",
"format": "",
"values": [
"Y",
"N"
],
"conditional": ""
}
},
{
"blockName": "999",
"name": "",
"startPosition": "",
"maxLength": "",
"minLength": "",
"data": {
"mandatory": "M",
"type": "int",
"format": "",
"values": "",
"conditional": ""
}
}
]
}
I apologise now if that is an affront to JSON users everywhere!
This works if there are both 001 and 002 lines in the file, but I've now been told that there may times when the file is all 001 or 002 but not both. Is there a way to make them optional? "oneOf" seemed likely, but I could not fathom how to use it in this situation.
My other issue was with the conditional entry. The data does not have a header row so I'm not sure how to check it. The intention is that if the 5th column contains a "C" then the 4th should have a date in it.
Any help would be gratefully received. Thanks