GEOGRAPHIC AND SEGMENT INFORMATION

Operating segments are aggregated into reportable segments only if they exhibit similar economic characteristics. In addition to similar economic characteristics, we also consider the following factors in determining the reportable segments: the nature of business activities, the management structure directly accountable to our chief operating decision maker for operating and administrative activities, availability of discrete financial information and information presented to the Board of Directors and investors.

Our reportable segments are disclosed as principally organized and managed as three operating segments: Core, OEM and Advanced Energy. We adopted reportable segments to align with changes in how we manage our business, review operating performance and allocate resources as a result of the growth in Advanced Energy and the differing behavior of the Core and OEM product lines. The Corporate & Other category includes certain unallocated corporate, operational, research and development and marketing costs which were not specifically attributed to any reportable segment. Net assets are shared, therefore, not allocated to the reportable segments. The OEM segment is primarily development contract and product driven, all related expenses are recorded as cost of sales, therefore no segment specific operating expenses are incurred.

Summarized financial information with respect to reportable segments is as follows:



	Three Months Ended March 31, 2018
(In thousands)	Core		Advanced Energy			OEM		Corporate (Other)			Total
Sales	$	6,519	$	2,629		$	768	$	—		$	9,916

Income (loss) from operations	1,856		(578		)	406		(2,548		)	(864		)

Interest expense, net	—		—			—		(34		)	(34		)
Change in fair value of derivative liabilities	—		—			—		(26		)	(26		)
Income tax expense	—		—			—		11			11
Depreciation and amortization	—		—			—		199			199



	Three Months Ended March 31, 2017
(In thousands)	Core		Advanced Energy			OEM		Corporate (Other)			Total
Sales	$	6,775	$	607		$	1,007	$	—		$	8,389

Income (loss) from operations ⁽¹⁾	2,213		(1,819		)	503		(2,634		)	(1,737		)

Interest expense, net	—		—			—		(31		)	(31		)
Change in fair value of derivative liabilities	—		—			—		88			88
Income tax expense	—		—			—		5			5
Depreciation and amortization	—		—			—		178			178


(1)	During the first quarter of 2017, marketing expenses were presented as attributable only to the Corporate (Other) segment in the line Income (loss) from operations. It was subsequently determined that certain marketing expenses are attributable to specific segments. The disclosure of Income (loss) from operations was updated for the first quarter of 2017 to reflect marketing expense by segment.

International sales represented approximately 19.6% of total revenues for the three months ended March 31, 2018, as compared with 16.7% of total revenues for the three months ended March 31, 2017. Substantially all of these sales are denominated in U.S. dollars. Revenue by geographic region, based on the "ship to" location on the invoice are as follows:



	Three Months Ended March 31,
(In thousands)	2018		2017
Sales by Domestic and International
Domestic	$	7,973	$	6,992
International	1,943		1,397
Total	$	9,916	$	8,389