BOISE CASCADE Co

12. Segment Information

We operate our business usingtwo reportable segments: Wood Products and BMD. We measure and evaluate our reportable segments based on net sales and segment operating income (loss). Accordingly, our chief operating decision maker reviews the performance of the company and allocates resources based primarily on net sales and segment operating income (loss) for our business segments. Unallocated corporate costs are presented as reconciling items to arrive at operating income. There are no differences in our basis of measurement of segment profit or loss from those disclosed in Note 15, Segment Information, of the Notes to Consolidated Financial Statements in "Item 8. Financial Statements and Supplementary Data" in our 2023 Form 10-K.

Wood Products and BMD segment sales to external customers, including related parties, by product line, are as follows:

(a) Amounts represent sales to external customers. Sales are calculated after intersegment sales eliminations to our BMD segment.

(b) Sales of EWP to external customers are net of the cost of all EWP rebates and sales allowances provided at various stages of the supply chain (including distributors, dealers, and homebuilders). For the three months ended March 31, 2024 and 2023, approximately 77% and 79%, respectively, of Wood Products' EWP sales volumes were to our BMD segment.

An analysis of our operations by segment is as follows:

(a) Primarily represents intersegment sales from our Wood Products segment to our BMD segment.