Sometimes the phrase 'Dark reaction' is used to refer co2 fixation. Why is this phrase inappropriate?

Photosynthesis reaction occurs in two steps:

1. The first step is a light requiring process which splits water and generates ATP and NADPH.

2. The second phase which is carbon dioxide fixation does not require light directly but uses the energy generated in step 1 which is light dependent. 

The second phase also called Calvin cycle was earlier referred as dark reaction. It means that this step does not need sunlight or light directly but it does not intend that the reaction does not occur during day time. Hence the phrase is inappropriate because this reaction can take place during day as well as night.