Derek,
The guideline from accounting principle to classify a purchase as CBP or expense are as follow.
1. Purchase items that have useful life less than one year is classified as expense. Purchase items that have useful life above one year is classified as CBP.
2. Purchase items that have useful life above one year but they will be use to repair the damaged fixed assets which don't improve capacity or efficiency of the said fixed assets is classified as expense.
3. Purchase items that will be used to replace the old/damaged fixed assets for the whole module is classified as CBP. But written off memo must be attached in the CBP Airwaves.
Any further questions or assistant please let me know.