A mechanics works on mining equipment at the Black Butte coal mine outside Rock Springs, Wyoming.

Job openings hit a fresh record in March, further defying opinion that the labor market is tightening and near full.

The level hit 6.6 million, according to the Job Openings and Labor Turnover Survey released Tuesday. Even though JOLTS figures lag a month, they are closely watched for signs of market slack. Job openings in total rose by 472,000 over February.

Openings jumped in professional and business services, which added 112,000 positions, as well as construction, with 68,000 and transportation, warehousing and utilities, which reported 37,000 new positions.

The openings happened during a month when nonfarm payroll hiring grew by 135,000, according to the Bureau of Labor Statistics, which releases both the monthly jobs report and the JOLTS survey.

Quits, an important indicator for whether workers feel comfortable leaving old jobs for new ones, rose to 3.34 million, up 136,000 from February. Gains were spread across geographic regions, with the South reporting 1.41 million.

Hires actually edged lower, to 5.42 million from 5.51 million.