Hi Carl
The posting date is called RefDate. Account segmentation is optional and allows a G/L account to have segments. The reason I ask is that segmented account are formatted as _SYS0000000..... numbers and not the usual G/L account number structure. In your case, ignore.
In order to check specific document types, use the TransType column. 13 is a Sales Invoice and 14 a Sales Credit Memo. There are plenty of references here in the forum to the TransType, so just do a search for a list of Document Types.
Hope this helps
Kind regards
Peter Juby