Custom Field / Post Settings

I’m new to coding and wordpress so apologies is this should be apparent whilst I learn.

Are the fields:
Source Name
Source URL
Via Name
Via URL

standard Custom Fields or have they been created in another way?

I was trying to get a plugin (that I use with other custom fields I have created to success) to post content into those fields and it could not locate them.

It could locate the custom fields I had created using there field name but not with the field names td_source, or td_source_URL

The plugin which I realise you don’t support only allows entries into custom fields. I can redirect it to a new location if they have been created in a unique location.

I realise you cannot help me with the plugin, but hope you can at the minimum advise of the nature of these fields, i.e. are they standard custom fields, and the field names i should be using for them.

Thanks.