Anthony asks about abstract particulars here. In reply, I am not sure what an abstract particular is, so I am not entirely sure I can answer the question. I don't think Ockham ever discusses such things, and in any case, beginning with distinctions in reality rather than distinctions in language is foreign to his whole project. When he begins to talk about 'concrete' and 'abstract' in Chapter 5 of Part I of the Summa, he is talking about types of term. He says that ‘concrete’ and ‘abstract’ are names that have a similar beginning verbally, but not similar endings. Thus 'human' and 'humanity', 'just', 'justice', 'wise', 'wisdom'and so on. This is a linguistic distinction, and Ockham's whole argument is that we confuse distinction in language with a distinction in reality. If Socrates is wise, then 'wise' denotes him, but so also does 'wisdom'. 'Wisdom' does not denote any common substance or nature, a singular thing common to all wise things. Rather, like 'wise', it denotes all wise things.
What about the distinction between particulars that exist in space and time (trees, chairs, people) and particulars which do not (triangles, numbers, etc)? Ockham does have something to say about this, but it takes up all of chapters 40-62 of the Summa, in his discussion of Aristotle's categories. So, more later.