Purdue previously used NFPA labels for secondary or lab labels. All labels must now use the Globally Harmonized System (GHS).   This is a lot of information to be included on small labels .  The information required on a GHS secondary label should include:
 

The information needed for the secondary label should come from the original container or the SDS for the material.   Multiple hazard statements may be combined to reduce wordage.   An important change is that all GHS labels must be printed in color.   The diamond surrounding the pictogram must be red.   This would require that the label is printed with a color printer or that stickers are used for the pictograms.   An empty red diamond without a pictogram inside is not permitted.

The only U.S. regulation about size of the label is that the pictograms and the text must be readable.   As a practical limit, text shouldn't be smaller than 6 point, and pictograms shouldn't be smaller than 9 mm (3/8 inch).   Other countries do have size requirements that are larger than this.

All HAZCOM areas must follow these labeling requirements.   CHP areas (chemistry laboratories) have more latitude in labeling requirements.