DETAILS OF CERTAIN BALANCE SHEET ACCOUNTS

Accounts receivable, net:



	March 31,
(in thousands)	2017			2018
Accounts receivable	$	184,068		$	202,270
Provisions for returns	(10,541		)	(10,225		)
Provisions for promotions and rebates	(31,747		)	(38,284		)
Provisions for doubtful accounts and sales allowances	(603		)	(873		)
Accounts receivable, net	$	141,177		$	152,888

Inventory, net:



	March 31,
(in thousands)	2017		2018
Raw materials	$	20,260	$	28,789
Work in process	215		450
Finished goods	34,981		39,037
Inventory, net	$	55,456	$	68,276

Property, plant, and equipment, net:



	March 31,
(in thousands)	2017			2018
Land	$	16,418		$	16,564
Buildings and improvements (useful life: 7-30 years)	115,909			115,401
Machinery and equipment (useful life: 2-10 years)	108,477			112,719
Software (useful life: 5-10 years)	46,806			50,631
Construction in progress	6,899			5,428
Property, plant, and equipment, gross	294,509			300,743
Accumulated depreciation and amortization	(144,202		)	(158,614		)
Property, plant, and equipment, net	$	150,307		$	142,129

Depreciation and amortization expense for Fiscal Years 2016, 2017, and 2018 was $19.9 million, $20.7 million, and $21.1 million, respectively.

Included in software are unamortized capitalized software costs relating to both purchased and internally developed software of $24.4 million and $23.6 million at March 31, 2017 and 2018, respectively. Amortization expense related to capitalized software costs in Fiscal Years 2016, 2017, and 2018 was $4.1 million, $4.4 million, and $4.9 million, respectively.

Included in construction in progress at March 31, 2018 was tooling for new products, machinery and equipment, building improvements at our U.S. headquarters, and IT-related expenditures. None of the items were individually material.

Accrued liabilities:



	March 31,
(in thousands)	2017		2018
Employee compensation and benefits	$	36,415	$	28,599
Accrued interest on 5.50% Senior Notes	10,407		10,331
Warranty obligation, short-term portion	6,863		7,550
VAT/Sales Tax Payable	5,433		5,353
Derivative liabilities	1,323		2,947
Accrued other	13,844		25,317
Accrued liabilities	$	74,285	$	80,097

Changes in the warranty obligation, which are included as a component of accrued liabilities in the consolidated balance sheets, are as follows:



	Year ended March 31,
(in thousands)	2017			2018
Warranty obligation at beginning of year	$	8,537		$	8,697
Warranty provision related to products shipped	9,451			9,923
Deductions for warranty claims processed	(9,824		)	(10,193		)
Adjustments related to preexisting warranties	533			1,177
Warranty obligation at end of year ¹	$	8,697		$	9,604

¹ Includes both short-term and long-term portion of warranty obligation; the prior table shows only the short-term portion included in accrued liabilities on our consolidated balance sheet. The long-term portion is included in other long-term liabilities.