Used (or "second-user"):
Suggests equipment which has at one time been supplied, installed and used at least once. This may mean it is anything from one month to 80 years old.

Unused:
Has never been fully commissioned, for whatever reason and may be still in the OEM's factory, delivered to site or long term storage location, installed or partly installed but never commissioned, or fully installed and pre-commissioned but never put to use. Some residual warranty or performance guarantee may be available.

New (or "As New"):
May be still in the factory, crated in storage, or installed but unused as above. Implies that the equipment is probably still under warranty, although the 'transferability' of such warranty may be disputed by the OEM or owner.

Cancelled-order:
Most likely to be still in the factory (or OEM's storage location), at an advanced stage of manufacture, or even completed and crated, ready for delivery, with the possible exception of certain ancillary items (e.g. fuel forwarding or gas receiving skids, NOx injection system, switch-gear, etc.). Usually with 'as-new' warranty and performance guarantee by negotiation, depending on site ambient conditions and fuel specifications.

"Advance or advanced-order":
May be at any stage in the manufacturing process, or even almost ready for delivery with final BOP (balance of plant) items such as fuel system, gearbox (which would be modified/bought-in to suit the desired frequency - e.g. W 251 Econopac or GE Frame 6 packaged units typically utilise a TEWAC alternator which can be run at 50 or 60 Hz).

Refurbished / overhauled:
Usually with such work undertaken by an OEM-owned or OEM-approved workshop or similar/competing facility with recognised/accredited procedures (e.g. Lloyds, ABS or Bureau Veritas). Limited warranty may be available on labour or parts replaced.

"Zero-houred" / Zero timed:
Fully refurbished by an OEM-approved or similar workshop to "as-new" condition, with a revised warranty on the overhaul work performed. Performance guarantees may also be available or negotiated, which would then be applicable to the new site.

"As-is" or "As-is, where-is":
Usually no refurbishment or overhaul has been carried out and the equipment is bought entirely at the purchaser's risk, with no guarantees, warranties (available or implied), "merchantability" or "fitness for purpose". It is also implied that any dismantling, disposal of unwanted auxiliaries, site clearance, etc. is solely at the purchaser's expense.