Come February 28 night, census enumerators will fan out across the city to count its homeless who sleep on pavements or take refuge under its many flyovers, at railway and bus stations and in shelters.
Unlike the three weeks dedicated to others, the homeless are to be counted all over Delhi simultaneously on February 28.
Similar headcount will be undertaken all over the country at the time to ensure that no one is left out in the crucial phase of Census 2011.
Homeless or "houseless" have been identified for the Census's purpose as those people "who have absolutely no shelter of their own to sleep in".
The 2001 census had put the figure at 24,966 in the national capital.
Surveys have already being conducted in August, September and October last year to identify the locations where the homeless take shelter.
Each and every inch of Delhi is technically going to be checked for this purpose. This is the method to minimise the chance of missing out.
The spots this time are expected to include major flyovers, railway stations, bus stations, temporary and permanent night shelters as well as some localities in Old Delhi among others.
The locations tend to change as the topography of the city changes, Joshi said, adding the homeless will be asked the same 29 questions as others.
NGOs active in the field have also been roped in for the effort with many of them providing inputs to census officials for the preparatory stages as well as spreading out a word on the date when the counting will be conducted. As NGOs will have better knowledge and sensibility on exactly how to approach the homeless and get the information from them.
Traditionally being a key part of this exercise, NGO workers will accompany enumerators on the rounds.
If there is some fear or apprehension in the mind of the homeless person then the NGO workers can remove that apprehension and see that the information is collected properly.
The Population Enumeration Phase of the 15th Census is being held all over the country from February 9 to February 28. Enumerators will be visiting households to collect data during the period.