What are the permitted compression techniques for PDF/A-1?

The PDF/A-1 standard does not specify how compression is performed. What are the permitted compression techniques for PDF/A-1?

The information I have gathered (not sure if all are true)

1. LZW should not be used
2. JPEG2000 may not be used
3. Few say, JPEG can be used but its a lossy compression. (PDF standard clearly states lossy compression can't be used)

Also, how to figure out whether a particular file is PDF/A-1a or PDF/A-1b and what kind of compressions are used in that file?

Thanks in advance.