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Summary of Significant Accounting Policies - Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
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Jan. 31, 2021 | Jan. 31, 2020 | Jan. 31, 2021 | Jan. 31, 2020
Total share-based compensation expense | $ 115 | $ 56 | $ 338 | $ 225
Engineering and Product Development [Member] |  |  |  |
Total share-based compensation expense | 32 | 12 | 91 | 52
Selling, General and Administrative [Member] |  |  |  |
Total share-based compensation expense | $ 83 | $ 44 | $ 247 | $ 173

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- Definition Amount of noncash expense for share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details
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- Details
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- Details
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