2004年，Skyline公司對Keyhole提起訴訟，控告Keyhole侵害他們的美國專利第6,496,189號專利，隨後Keyhole被Google所收購，訴訟案也轉到Google頭上。

Skyline宣稱Google的3D地貌(three-dimensional terrain visualization)軟體也同時侵權(例如Google earth)。一般認為，Keyhole的3D地圖技術是Google在搜尋引擎之外最成功的技術，因為Google earth至少已經被下載一億次以上。

在法官Woodlock聆聽完系爭專利的claim之後，Google提出了沒有侵權的論點，其中有一項有趣的論點是Skyline的方法項中提到，資料會被轉換成「renderer」。

Claim 1. A method of providing data blocks describing three-dimensional terrain to a renderer, the data blocks belonging to a hierarchical structure which includes blocks at a plurality of different resolution levels, the method comprising: receiving from the renderer one or more coordinates in the terrain along with indication of a respective resolution level; providing the renderer with a first data block which includes data corresponding to the one or more coordinates, from a local memory; downloading from a remote server one or more additional data blocks at a resolution level higher than the resolution level of the first block which include data corresponding to the one or more coordinates if the provided block from the local memory is not at the indicated resolution level.

儘管Skyline強調Google在許多地方使用到renderer，但Skyline自己都沒有辦法定義何謂renderer，法官Woodlock認為Claim中使用了一種元件加功能的寫法，並不代表能使專利的權利擴張到所有具有此功能但不同的元件都落入了這篇專利的範圍，即便他們達到的結果是相同的。

當然，身為耶魯法學院的畢業生，Woodlock總會把葉慈(Yeats)放到判決書中：

Skyline's ultimate position, as presented at the summary judgment oral argument, appears to be that the Google Earth Client, a "software application, running on the local processor," itself "performs the three renderer functions." . . . However, Skyline also suggests that unspecified pieces of the Google Earth Client source code perform the functions of the renderer, suggesting a more granular definition . . . In either formulation, the Skyline position, which I reject, erroneously conflates the functions of the renderer with the separate thing that is a renderer. This takes considerable and unwarranted poetic license with the Markman construction and, as I noted during the hearing on the motions, calls to mind Yeats’ question: "How can we know the dancer from the dance?" W. B. Yeats, "Among School Children, The Collected Poems of W.B. Yeats," 215, 217 (Richard J. Finneran ed., rev. 2d ed. 1996).

Translated form Peter Zura's 271 Patent Blog

判決之外：means plus function寫法的限制。

Means plus function claim，aka 112(6)，手段附加功能寫法，起源約在1990的美國，由於方便撰寫並且能有效描述許多結構抽像的技術，因此廣為流行，通常被使用在電路專利以及軟體專利中，在20世紀末這些使用,means plus function寫法的專利漸漸進入了訴訟期，人們才發現以這種寫法寫成的專利在文義讀取(claim construction)上會有很大的問題，因此許多人開始反對這種寫法，台灣也有許多事務所主管不建議使用功能去限制元件，即是由此而來。但就某些技術而言，means plus function仍是唯一可以有效保護技術的撰寫方法，因此到目前為止仍被廣泛的使用著。

一般這種寫法的特徵為：元件/手段 + 功能