/ Other Performance Metrics
| (in millions, except percentages) | Q1 2021 | Q1 2020 | % Change | % Change in Constant Currency | |||||||||
| ACV | $ | 319.4 | $ | 301.1 | 6 | % | 3 | % | |||||
| Operating cash flows | $ | 171.1 | $ | 147.4 | 16 | % | |||||||
ACV is a metric the Company uses to better understand the business. There is no GAAP measure comparable to ACV. ACV is composed of the following:
- the annualized value of maintenance and lease contracts with start dates or anniversary dates during the period, plus
- the value of perpetual license contracts with start dates during the period, plus
- the annualized value of fixed-term services contracts with start dates or anniversary dates during the period, plus
- the value of work performed during the period on fixed-deliverable services contracts.
/ Management's 2021 Financial Outlook
The Company's second quarter and fiscal year 2021 revenue and diluted earnings per share guidance is provided below. The Company is also providing its fiscal year 2021 guidance for ACV and operating cash flows. The revenue and diluted earnings per share guidance is provided on both a GAAP and non-GAAP basis. Non-GAAP financial measures exclude the income statement effects of acquisition adjustments to deferred revenue, stock-based compensation, amortization of acquired intangible assets and acquisition-related transaction expenses.
The financial guidance below reflects the Company's current estimates of the adverse impacts of the global pandemic and trade restrictions. This guidance is based on the Company's evaluation of factual information it has determined to be relevant and the application of certain assumptions made by the Company. Please refer to the Company's prepared remarks document for essential additional information regarding the Company's financial guidance, including its assumptions regarding overall business dynamics and the economic impacts of COVID-19 and trade restrictions.
/ Second Quarter 2021 Guidance
The Company currently expects the following for the quarter ending June 30, 2021:
| (in millions, except per share data) | GAAP | Non-GAAP | |
| Revenue | $409.7 - $439.7 | $415.0 - $445.0 | |
| Diluted earnings per share | $0.82 - $1.10 | $1.43 - $1.67 |
/ Fiscal Year 2021 Guidance
The Company currently expects the following for the fiscal year ending December 31, 2021:
| (in millions, except per share data) | GAAP | Non-GAAP | |
| Revenue | $1,790.7 - $1,855.7 | $1,810.0 - $1,875.0 | |
| Diluted earnings per share | $4.62 - $5.16 | $6.69 - $7.10 |
The difference between the GAAP and non-GAAP revenue guidance presented above is a result of the expected impact of the application of the fair value provisions applicable to the accounting for business combinations in the amount of $5.3 million for the second quarter and $19.3 million for FY 2021.
