The word sigrdrifa can be read as a compound meaning something like driver or bringer of victory, which is exactly the kind of descriptive term Old Norse poetry applies to valkyries generally. It can also be read as the personal name of one particular valkyrie. The manuscript does not decide it, and editors have gone both ways for two centuries. Nineteenth century editions often printed it as a name and titled the poem accordingly; a number of later editors treat it as an epithet and take the figure to be unnamed in the verse itself.
That matters because of who else is in the cycle. The Volsunga saga and Snorri's prose both identify the valkyrie whom Sigurd wakes with Brynhild, and the prose links inserted between the poems in the Codex Regius encourage the same reading. If sigrdrifa is an epithet, the identification is easy. If it is a name, the tradition holds two separate women whom Sigurd meets on a mountain, and the cycle has a duplication in it.
The cycle has other duplications, so neither answer is decisive. The verse material about Sigurd, Brynhild and the Gjukungs was assembled from poems of different dates and regions, and it contains episodes told twice with different names and motivations. Whether this is one of them is genuinely unsettled among editors.
The atlas therefore holds Sigrdrifa as her own entry while recording the identification as disputed, which reflects the state of the argument rather than settling it.