(indicated at 0 VU and −8 PPM) and tone bursts at +16 dBu (indicated at 0 VU and 0 PPM). Canada By 1978 PPMs were in use at the Canadian Broadcasting Corporation's Vancouver plant. Some 30 or 40 PPMs were in use, with just one or two VU meters retained for settling telco disputes. These are Type II PPMs with the seven marks labelled −6, 0, +4, +8, +12, +16 and +20: this scaling shows absolute levels in dBu (or dBm into 600 Ω). The appearance is similar to the ABC PPM except that all the numbers are 16 dB higher. South Africa The South African Broadcasting Corporation (SABC) uses a Type II PPM modified with a black-on-white scale plate calibrated in percentage and dB relative to Permitted Maximum Level, which is +6 dBu. Alignment Level is 0 dBu or 50%. IEC 60268-18 Digital PPM IEC 60268-18 is a partial standard for a PPM designed for use with digital audio in both professional and consumer use, using "incremental dot or bar type displays or numerical displays". Such a display shows level relative to 0 dBFS. The integration time can have any value less than 5 ms − thus both true-peak and quasi-peak meters can comply, and different meters may indicate very different levels despite compliance with the standard. The return time has the same value as a Type I meter: 1.7±0.3 seconds for a 20 dB fall. Table of characteristics IEC 60268-10 specifies three variants: Types I, IIa and IIb, known colloquially as the DIN, British and EBU types respectively. Types IIa and IIb differ only in the scale marks. The Nordic, ABC, CBC and SABC variants are not specified in IEC 60268-10. The Nordic PPM uses Type I ballistics with a different scale. The ABC, CBC and SABC variants use Type II ballistics with different scales. Parameters for the VU meter and Nagra modulometer are included in the table below for comparison. Some information has been obtained from ITU-T Rec. J.15. Nagra modulometer The 'modulometer' is a proprietary type of quasi-PPM found on Nagra products. It has an integration time (−2 dB) of 7.5 ms, and a semi-logarithmic scale with an appearance between that of a VU meter and a DIN-type PPM. A stereo version ("double modulometer") uses a meter movement with two coaxial needles. In typical practice for Nagra analogue tape recorders, Alignment Level is regarded as −8