In a webinar titled How to Calculate Your FAS 5 Reserves, Abrigo discussed the difference between ASC 450-20 (FAS 5) and ASC 310-10-35 (FAS 114) loans.
From the video: What is the difference between ASC 450-20 and ASC 310-10-35 loans? In order to understand ASC 450-20, it is important to understand what it is not, as well. ASC 450-20 and ASC 310-10-35 are the two underlying accounting guidances factoring into your ALLL calculation. Where ASC 450-20 is homogenous pools, ASC 310-10-35 in contrast is individual loans. So in ASC 450-20 we are grouping together loans that are deemed non-impaired. We are going to put them into buckets of similar type loans. In ASC 310-10-35 we are going to separate out those loans that we deem impaired, and we are going to look at those individually (as opposed to applying a standard loss rate across a homogenous pool). As far as the next line item - the general reserve versus the specific reserve - the ASC 450-20 is a general reserve. We are basically saying that we are not going to look at each one of these non-impaired loans individually - substandard or greater typically - we are going to just group them into homogenous pools, we are going to look at a historical loss rate, and we are going to apply it against those homogenous pools in order to determine a general reserve. The ASC 310-10-35 is the alternate side of that. These are loans that we need to look at more specifically due to their impairment status. We are going to identify on a loan-level basis the total recorded investment into a loan, contrast that with whatever underlying value that we anticipate receiving over the life of the loan, and from there make a determination on a specific reserve, loan by loan. Non-impaired loans, or our ASC 450-20 pool, are loans that generally are substandard or greater, and are not impaired. ASC 310-10-35s would be those loans that are impaired. The underlying guidance basically defines impairment as such where it is not expected that you will recover all contractual payments due, including any principle and interest. Basically we are saying that if we don't think we are going to get everything we have into the loan, it is impaired.

To sum up: ASC 450-20 is basically homogenous pools that we apply a general reserve against, and these homogenous pools are made up of non-impaired loans.