Tag with 'NFC-A' and 'ISO-DEP' technologies but not recognized as ndef-compatible

[Honry]

I have a tag (see following image read from native nfc app), with 'NFC-A' and 'ISO-DEP' technologies and no NDEF message, which is type of NFC Forum Type 4, per spec https://w3c.github.io/web-nfc/#ndef-compatible-tag-types, my tag should be one of ndef compatible tag types, but which couldn't be read/write from both native nfc app or Chrome, when writing with native nfc app, it throws with "Non-ndef compatible" error.

[leonhsl]

By my understanding, this tag should just be ndef compatible because of the NfcA technology it carries.

Could anyone help clarify the phenomenon here?

[kenchris]

Is is formatted as ndef?

[Honry]

No, it could not be formatted as ndef.

[zolkis]

AFAIK they MAY also expose NDEF, but not required to do so.

[Honry]

So a tag is of NFC Forum Type 4 may be NDEF compatible, but a tag without NDEF technology (e.g. my tag with only "NFC-A" and "ISO-DEP" technologies) must be NDEF non-compatible, right?

[kenchris]

as far as I understand all NFC tags should support ndef, but I might be wrong - or this might be an issue with the tag. But as this is outside our scope I am closing