That's the lot just near the El tracks and Nacional 27 right?
"DS, Downtown Service District
accommodates commercial and service uses that are essential for the
livelihood of businesses and residents of the downtown area and surrounding neighborhoods. "
A site I found says the following:
"The primary purpose of the DS - Downtown Service District is to accommodate commercial and service uses essential to businesses and residents located downtown and the surrounding areas. This district allows for a mixture of small-scale office, commercial services, public uses, transportation services, communication services and industrial uses. "
http://chicagocouncilmatic.org/legislation/1525666